This seems like it would be a fun project. Does anyone know where I could find a write up or a build up of a VG30DETT into a 620?

I already have the motor, and 620's go for around $600-$1500 around here.

If I had the truck, how much money do you think I'd need to put my VG30DETT into the 620?

That motor is awfully wide. I've seen the VG30E in 510s, 521s, 620s, etc. but the VG30DE(TT) would be tough in one of those. It barely fits in the Z32 or the J30 and those cars are much wider than the trucks.

Welcome Kaleb! I would love to see this done.

Biggest issue I'd think you'd have is getting the engine to sit between the framerails and still be able to route exhaust. The twin overhead cam engines as stated are really wide. The dimensionally similar VQ35 is even a tough fit into a D22 chassis and required custom exhaust manifolds to be built when Nissan built their project X Xterra back in 2001.