4/6 drop ?

[fast67chevy2002]

I am about to send off my swb frame to have it coated. Is it better to do the drop before or after. and also who is the best to go through for a 4/6 drop complete drop kit and c-notches.

with the 4/6 drop is it better to use a 4-link hookup and if so which one. I have had a few people tell to use the one with one bar on each side of the diff. on the top of the axle. and others telling me to use one with bars on top and bottom of the axle. Which is better

I still have the original I beams that came on it. Is it better to use those.

Sorry for all the ?'s

Thanks for any help you guys can give.