I'm also building a (relatively) low buck 340. Have already the basic parts except the cam and the pistons. I intend to keep it simple, flat top pistons and either a solid flat tappet or roller cam with a single E85 carb. The heads are brand new (NOS?)closed chamber W2's bought from moparts forum that I will try to port, the crank is a stock 340 unit and the rods H-profile steelies. Mahle offers pistons, they have coatings & rings included and from what I've seen are good quality, light list pistons. They should provide CR between 11.5 -12_1 depending of the gaq between the head and block. Haven't thought much about the cam yet since still in early stages, the car will weigh around 2600 lbs with driver and the rest of the drivetrain is a doug nash maual and 8 3/4 with ladder bars.