It's a good possibility. Not because you installed it like a Chevy, cause it's the same procedure on all American V8's. The problem is you didn't degree in the cam like Cudafever said. The issue comes in where the timing chain set may have been built retarded and/or the cam may have not been ground properly. I don't even rebuild a stock engine anymore without checking the cam timing.
It is entirely possible that it is degree'd correctly but you just never know. If it's 4 degrees retarded that will cost you quite a bit of bottom end torque. top that off with the airplane gears and you've got a dog out of the hole.
IMO you need at least 3.73 gears for your combo.
Also more timing might help. Have you experimented with the timing to see where it runs the best?