I would suggest that you phone SailWarehouse in California who can answer those sail-slug questions while you wait. I recently got a 135 and an inner jib from them, made by Rolly Tasker, and can't say enough about the quality and service.
I don't recommend loose-footed mainsails unless the rest of the boat has been designed for it. In fact from an engineering view the traditional system of sail slides in the boom is massively stronger. End-loading a (40-year-old) boom not designed for it is asking for trouble especially if you do not have end-boom sheeting. The vang, also, will bend the boom horrifically.
In fact, with a loose-fitted main, the vang is really not even needed. What does it do then? - it's not adjusting anything about the sail at all. If anything, tensioning the vang with a loose-footed main only ADDS pocket or bagginess - its original purpose was to stiffen the lower forward 1/3 of the sail, which is where undesirable bagginess happens on traditional mainsails. Given a loose-footed sail you can adjust this with the outhaul. And you can't do much else for the sail shape after that. Worse, if you do not have end-boom sheeting, you're adding even more bending moment to the boom which can lead to potentially catastrophic failure of the (40-year-old) extrusion.
Those who are constitutionally skeptical when I say stuff like this may be enlightened by the fact that Selden went to reinforcing their booms for use with end-loaded/loose-footed mainsails by the incredibly boneheaded measure of adding, to inside of the extrusion, a lengthwise horizontal plane, to make it resistant to lateral bending - which happens, and cannot be stopped otherwise, when the whole after half of the sail falls off to leeward through bending the extrusion between the outhaul point and the sheetline. But then some of those Beneteau buyers insist on such huge Bimini tops and other things to avoid the 'inconvenience' of the mainsheet in the cockpit (at the end of the boom where it belongs) that the boats have sheetlines mounted LESS THAN 50% of the boom's length back from the gooseneck! And then they fit a massively expensive hydraulic vang! (or, worse, a Boomkicker.)
I started in this industry in 1972 and I'm a pretty clever guy; but I seriously do not understand the mentality of some people at all. My dad would roll over in his grave. His philosophy might be summed up:
complication + weight + expense = not sailing.