mini tub

I'm jumping into the mini tub on my 73 Swinger and have a few questions for the dudes that have done it. I got a great deal on a whole 8 3/4 rear end from a friends 74 Duster that was narrowed 7 inches and he ran a 15 x 12 inch wheel with a 5 inch back spacing so thats the size rim I will be looking to go with (for reference on the second question).

First is the trunk hinges, should I just chop them off and convert it to a pin on lid? That looks like it would be easiest but would like to keep it hinged if possible.

Next is how big should I really go, as in what is the nominal size for the tires on a 15 inch rim (410 gears with a 3800 stalled 727 that wants to see some street and highway driving - might step down to 373 gears but not too soon)and how big of a tub will there need to be to allow for it. Summit has three sizes of tubs avalible but too big would be a waste of space and would probably make me have to cut out the truck hinges.

I'd ask my "buddy" that i got it from directly but we havent talked for a while for various reasons and hes hard to get ahold of in any case so any help would be greatly apprciated. Thanks!

-Sefus