I say keep the 50-trim. The center section is better and you have more usable power on the street. As far as building the motor, if you have a 6-bolt I wouldn't consider that an issue

IMHO if you have a setup and you're happy with it, leave it. It's summer! Keep the car on the road, drive it, have fun, etc

Have you looked into how to get more out of your 50-trim? E85 or alky injection? Bigger cams, tuning, SMIM, etc?