I have a Mallory "Flattop" in the '51 mercury engine in my '51 Ford club coupe, along with a set of reworked Edmunds heads and a Rochester 2G carburetor. I drive the car a lot during the summer and do not have a single complaint about the way it runs and drives. I think it comes down to proper setup and maintenance. It's a good thing it does, because I much prefer it's looks over a converted SBC unit (unless the converted distributor is a Mallory
).