Not a source for spam cans, but

http://www.freundcontainer.com/product.asp_Q_pn_E_211EZO_A_EASY%2DOPEN+ENDS+%28ALUMINUM%29+FOR+CANS

here is a source for easy open tops for round cans. Of course the problem is you have to have a can sealer.

I would think you would have to have a special sealer to handle a can that is not round. Even if you found the cans and lids, I don't know if a regular can sealer would work.

It has been a long time since I have had any, but someone may know, how is General Foods International Coffees (A sweet, flavored instant stuff) packaged now. They once came in a tin about Spam shape, maybe a little smaller, with a press in lid.