Will i be able to use my old 440 oil pump drive with the 400 based motor ?

Hi Mick, yes they are the same except,

1. some oilpumps require longer lengths to engage the pump,
the pump manuf. should tell you this.

2. roller cams require bronze gears on the drive to work with the roller cam cores.
Don

Thanks Don
I have two anyway same length both used with the melling hi vol pump, one with the bronze gear and the other out of the short block you sold me.
Mick