Hello 460fanatic23 and welcome to the Ford Forums,
That's a very nice quality Canton front sump oil pan and pickup that you have. (If you purchased it through eiither Canton or Ford Racing, it is made by Canton.)
Although it is indeed a front sump style pan, Canton designed that front sump pan to be used with a rear sump oil pump. This is obvious by the pickup tube configuration. You need to use either the M84D
or the M84DHV
oil pump as offered by Melling.
Generally, I have a preference for HV pumps, but you have not detailed your build. Is this 1991 F250 460FI engine going to be rebuilt as an all stock engine and re-installed into an F250? If so, then the standard volume pump will do fine. But if you are building an engine of much higher performance, then you might want more oil pump.
Please describe your build a bit more....intended horsepower, max rpm, comrpession ratio, primary use of the engine (street/strip, drag race only, towing, etc). Then we can help you to select a proper oil pump for your combo.