Yes you do have to fabricate mounting plates. The pictures in the installation booklet I sent out show those. I did my install several years ago and don't have the exact measurements but here is what I did.
First, you need to purchase mild steel flat stock (you don't need stainless since the entire engine and Beta mounts are made from regular steel anyway). Get the steel long enough to cover the length of each of the Vega mounting beds. The width should be such that they are slightly wider than the bed. The thickness, probably 1/4 inch, maybe a little thicker (enough so you can tap a good thread). Steveb probably has the exact measurements. and when I am on the boat this weekend I will measure them and report back.
Measure the exact location of the existing mounting holes in the engine bed (I believe they fiberglass a metal bar inside the bed as these holes are tapped). Then drill holes in the steel plates to match those holes. Then figure out where the Beta mounts will be attached and drill and tap mounting holes for the mount fittings. One note, I didn't have a very good drill and tap when I did the first hole (one I had purchased as some store catering to amateurs) and it was miserable drilling the first hole even with cutting oil, and I broke the first tap). But then I went to a bolt store (Tacoma Screw in the Seattle area) that caters to the pros. I bought an expensive bit and an appropriate tap for the hole to match the mounting bolts actually).
When I went back to drill the next hole it cut through so fast I couldn't believe it, like drilling through wood). Anyway, once that is done, I sprayed the plates with some good zinc based paint designed for this purpose, then sprayed them again with white paint. I bolted the plates to the Vega beds.
To get the Volvo out and the Beta in I build a very crude cradle to sit in the cabin out of some scrap 1X8s and a piece of plywood (the engine has to come out the companion way). I had another fellow helping and I used a
sling from the boom to take up a little pressure (tip -- take your main
halyard directly to the sling on the boom to take up the pressure so
there is no horizontal leverage on the boom -- secure the sling fore and aft with a small line). I made another little bridle from some halyard line I had lying around. Then we worked the Volvo onto my crude cabin cradle. Then after my blood pressure returned to normal, the crane lifted the Volvo out as I guided it. Putting the Beta in was the reverse process. The Beta weighs much less than the Volvo so it was much easier. (However, seeing my several thousand dollar engine dangling 15 feet in the air was heart stopping.) Then it was a simple matter of sliding the Beta off my little cabin sole cradle and onto the engine bed. I guess SteveB has lifted the engines in and out with the boom, but I had the boat in the yard and I am too old to deal with that (the yard crane cost me $75 for the time to do the work, much cheaper than paying for a heart attack!)
Couple other thoughts. When I did mine I took a small drill press right down to the boat. Oh one other thing that made my life easier was that I have a friend who rebuilds old cars and I borrowed his engine crane to get the Beta in and out of my pickup bed (take off the tailgate and you can roll the engine well into the bed). If you need to you could rent one from most rental stores (or buy one for a few hundred from a place like Harbor Freight (USA chain) -- amazing how handy they can be around a shop and they do fold for storage).
Oh, I was asked what I did with my old Volvo (that was really toast and needed a few thousand dollars of repair if it was ever going to work). I belong to an organization that teaches dozens of courses on boating, from navigation to electrical to engine maintenance. The engine maintenance instructor was thrilled to get my old Volvo as he could use it in his course. He took everything I took out of the boat including the old water lift muffler. Oh, and Beta sells a great fitting that goes from the transom mount, straight up and then the exhaust hose attaches to that, so no big loop is needed (don't know what it is called). They also sell a transom fitting that requires a hole exactly the size of the outside measurement of the exhaust fitting that is on the beta. So it was simple to take a hole saw around the fitting and drill it out of the boat, much simpler than trying to unbolt the existing fitting.
That was my experience. I am sure others have different methods and far more experience.
