That would be a lower compression 340 if it still has the stock internals. The factory intake is so good that unless you have an edelbrock rpm or an old Edelbrock LD340 handy, you’ll be ahead running it. Those are all good cams, but the one that will work best depends on how far you’re going to go from stock with it. Some will probably require machine work for the lift. junkyard hero pretty well nailed it on those, and everything else, too. Do you plan on going back with stock type pistons? I would plan on going back together with at least 9.2:1 compression. If it’s needing an overbore, it would be a good time to upgrade them. You said stock 727, are you planning on a factory high stall converter or an aftermarket option?