Could create problems
The extra 8" of height isn't a problem, but the distance from the heads is likely to be. The optimal distance from head to tank is <6'...anything over 8' is likely to leave waste sitting in the head discharge line to permeate it or build up in it and clog it. Whether the engine room location is likely to be a problem depends on how close to the engine and how much heat. However, distance from the hull is even more important, 'cuz that's gonna affect the length of the tank vent line...if you want to prevent odor out the vent every time you flush, the vent line needs to be as short (ideally 3' or less), straight as an arrow, and as horizontal as possible. Inlet and vent fittings locations on the tank are also important to prevent runback toward the toilet and/or spilling out the vent while heeled. So we prob'ly should discuss what you want to do in more detail via email. There are two more issues you seem to have overlooked: I see you're in Toronto, which seems to put your boat on the Great Lakes...in which case forget installing a macerator to dump a tank 'cuz you're at least 700 miles from any waters in which you could legally to use it. The Great Lakes and all inland US and Canadian waters are strictly "no discharge"...holding tank that can only be emptied by pumpout is the only thing that's legal. To legally dump a tank, you must be in open ocean at least 3 miles from nearest point on the whole North American coastline. Your Groco HC toilet became obsolete two versions ago...the current version--HF has been current for nearly 15 years, with an HE version in between for about a decade. So I think it's prob'ly time for a new toilet, 'cuz the only parts still available are a rebuild kit and an "upgrade kit" that's actually a whole new pump assembly plus adapters that'll cost you more $$ than a brand new HF. If you want some help spec'ing out the best way to give more more capacity where you need it, email me...I'm in the directory. You might also check out the link below.
