Got a 1990 cummins with a bd diesel fuel pin was gonna switch to the m&h m2 pin can I keep the bd gov spring in with the m&h fuel pin

 

Yep!

 

You will need to readjust your star wheel and smoke screw. Set the star wheel so the pin drops into the deep part at 10-15psi boost. Set the smoke screw so the flat spot in your off idle power just goes away. Seems to work quite well in that position.