I was running that pump up until I rebuilt my engine. I had a pump test done while the engine was on the dyno to see if the pump could handle my set up. In my case I had to upgrade my pump. Im running a Carter M6270 now, which needs a regulator. You dont have to run a return line with a mechanical pump, but if you have everything there to do it, it can not hurt.
I have never found a mechanical pump with return line provisions, I did find racing pumps with larger 3/8" NPT, but how many horses are you talking about running? Do you have an idea in mind for what your looking to get out of your engine when you rebuild it? Stroker, high horsepower, stock, ???
The stock pump that you were running will handle a stock to mildly built engine. Some even use it on moderate engines.
