They will be so close in performance, with a slight edge going to the -227 at the higher revs.
I may be inclined to vote for the 501 simply because it will be easier on the valvetrain with 1.6 rockers due to the more conservative exhaust lift. If you're running 1.5 rockers, I'd go with the Crane 227.
I expect the 501 with 1.6 rockers will beat out the 227 with 1.5 rockers across the board.
^^ what he said. I was gonna use a 227 in my build, but I will be using 1.6 rockers on my stock cam, so I will end up with a 500-502. The 501 might have the slight edge, because I believe, BELIEVE, that the 500-503 cams have a faster ramp. Meaning they reach peak lift sooner, so more area under the lift curve. I'm still working on hard data to back this up, tho, so don't qoute me. The flow on stock heads really seams to level off after .500" of lift. So a bunch above it isn't helping as much as it seams. If you look a few pages up you will see a thread "cams and 1.6 rr", I listed alot of popular cams, and the lifts after deviding by 1.52, 'times' 1.6. I should in no way be condsidered a cam expert, mostly thinking out loud.
I used the 501 cam in a mild, cast crank, 383 with stock rocker arms and ran consistent 12.0's and a fastest 11.81 at Cecil in good air.(see ET page) So I kinda like the 501. Very easy on everything, including mpg.