basic rebuild ... possible?

Can you do a cheapie rebuild - well it depends on the condition of the pistons, and the block.

For the coverter issue use a counter weighted flex plate - I think B&M or one of the other trans outfits sells them, then you can use the 904 as is.

To check the cam, pull the lifters out one at time and look at the bottom surface that rides on the cam itself. If you see a circular wear pattern then its good. If you see a straight line running across the wear surface its going bad. This tells you whether the lifters are spinning as they are intended. Keep the lifters in order as you remove them, if you intend to reuse the cam and lifter as a set. The lifters can be dis-assembled and cleaned.

The critical thing to check on your pistons are the bore sizes, if they are less than .010" greater than the specified bore size, in this case 4.000 or 4.010" max. Then you'll be okay rebuilding the motor with those pistons. Another item to check are the ring lands, the fit of the rings in the piston grooves, check this with a feeler guage, they are supposed to be about .003" or less clearance, check them with the old rings before removing the rings themselves.

Obviously the less wiggle you have in the bores and the tighter the ring lands are the better off you'll be. Be sure to put new cam main and rod bearings in the block along with new freeze plugs, timing chain, and oil pump. Ive also honed a block myself using a three arm hone with a variable speed cordless drill succesfully. You can save a little money that way if you are willing to try it. be sure to use the correct grit stones for the type ring you end up using.

While disassembling the engine check the bearing clearances with plastic guage. This will give you an indication of the wear on the crank. Once apart you can polish the journals yourself using a very long leather shoe string and 600 emery paper, wrap a piece of paper around the journal and then wrap one full revolution of the leather shoe string around the paper, pull the loose ends back and forth thereby moving the paper back and forth around the journals. If the journals are gouged up badly all bets are off.

On the heads you'll have to check them out. You can do a backyard mechanic test by putting the spark plugs back in and flipping them over with the combustion chambers facing up. One at a time fill the combustion chambers with gasoline and watch to see how long it takes for the gas to leak past the valve seats. If it takes more than 1-2 minutes and very little leakage then the seats are okay. If it leaks then you can tell which valve because it will leak back either on the intake or exh port. personally I'd have a low buck valve job done, knurl the guides and have the valves reground. Its really hard to do a valve job without a hot tank and the proper equipment.

Have at it and let us know what you end up with.