Originally Posted by Stream_Punk
I finally did some poking around the '85 Sovereign
. This is what I found under the toilet.
The toilet is only 12" tall off the top of the 'box'. A short search on the internet finds 'low-profile' toilets ranging from 13-15" tall. I already feel this toilet is too tall and wife is 10" shorter than I. I may look into modifying the black tank by removing the wedge and replacing it with a patch and a floor mounted flange to place a 'china bowl' type unit in it's place.
Cutting off the "wedge" and patching it is not likely to go well. It's difficult to get any type of adhesive to bond with the plastic that the tank is made of. Chances are you'd end up ruining the tank and needing a replacement.
Best bet would be a low profile toilet with a small step in front of it to aid with the height issue.
Second best bet would be to replace the tank with one that will fit under the floor flush with the fittings in necessary positions.
Third best bet, cut as you described use a lot of sealant between the patch and tank and stainless screws to hold the patch down. It should never be under pressure and is on top of the tank do the leak potential is low, but you want to be sure it's water/gas tight. A piece of plywood over the top spanning to the floor to keep the toilet weight off of the tank fitting itself.