Oh man, now you're talking REAL horsepower instead of the I-gotta-be-revving-10000RPM-to-burn-the-tires horsepower! LOL!!!
But seriously, V-8's are a whole different world from in-line or even V-6. A 340 Magnum, short of the newer Mustang V-8s (you know it killed me to type that!
), is one of the sweetest small V-8's out there. The only problem with a built 340 is it's hard to make a sleeper when the vehicle is limping right-left-right-left, though you can quiet them down with modern mufflers and hope no one notices the Thumper Shimmy. The hardest thing with shoe-ins is getting the intake in there. Nothing says "I'm here!" quite like a breather sticking out of the hood - but a mild blower with a side-mount TB might fit ...