Riddle me this..mechanical vs vacuum advance

Ok so I have another thread in here about troubles with my La based 408 stroker having troubles staying running in gear at low rpm, and what appears to be a fouling issue of the plugs. It’s a blueprint 408, that I bought never run, from a 3rd party. The tech from blueprint got back to me with some inquiries I had about the motor build, and in his response he said “timing needs to be mechanical only, no vacuum advanced used.”
When I got my motor, it has an msd distributor in it with vacuum advance and that is always how we have tried to time it. I’m assuming the shop I bought this motor from added the msd vacuum advance distributor. Would running vacuum advance and trying to time the motor with it cause any of my issues? Sorry if it is a dumb question, as any old car I have ever had, they all had vacuum advance.