This won't make much power with those cams and compression, at 5200ft. The big thing is the heads and compression.
unless a decent throat cut is made and you really know how to port, the heads are going to be weak in low/mid lift flow and probably would be better off porting with stock valve sizes with such small cam and limited porting ability, and if you do use the 1.88...open the runner to 360 sized port window. You are gonna be foot deep in iron dust fyi
I get everything your saying, except what you didn't say. What is "much power"? The op is looking for a driver, not a 12 second car. I agree, I would cut the heads in that altitude. However, I think the op will be happy for what he is expecting.
Oh, by the way, I did a throw together 318 for my brothers Demon in Loveland, Colo (about the same altitude) a few years ago. I did the MP .474 cam, cut .040 360 heads that were home ported, and 4bbl with hedman headers. Short block was never taken apart. He out ran a mid - nineties corvette (4 exhaust pipes in the center), along with some other stuff. He had 3.55's and an 11" TCI breakaway converter. All used parts, including the 318 2bbl we started with. He was happy for the few cents he threw into it. I think the op will be happy also.