I've built a few of them. Only one was a kit. Customer supplied from Mancinin Racing. It used a Callies Dragonslayer crank, Eagle H beams, and Diamond pistons. I was very happy with it. The others I pieced together using MP cast crank. I would buy a kit from hughes if they dont actually unbox anything. I dont trust thier machining or customer service anymore. AS far as hints. Measure everything. Callies and MP have always been spot on. Scat, Eagle, and Ohio Crank parts have been known to have issues. (kind of weird, because I think Scat or Eagle makes the MP ones...) Stay away from Scat rods, or check them well, after properly cycling them. I wont use Eagle SIR rods for anything. I'd rather have stock rods with ARP bolts in mild applications. I dont external balance. It's a factory production procedure that isnt very good, it's just good enough. Forged cranks will balance easily, cast ones will need mallory to internal balance. Dont use anything but a quality forged piston. The piston speeds with a 4" arm are too fast for anything else, even in low rpm (under4K) applications. Youer heads are better than Edelbrocks. How much better depends on the porting. W2s are a better head right out of the box, but more pricey. Your cam, intake and carb will act much smaller with the 4" arm. Cams under about 230° @ .050 generally idle very nicely, and pull a ton of vaccum.
