Scarebird Disc - What Master?

So I decided on the Scarebird route for my disc conversion, but a few questions on the Master:

They suggested a late 80's early 90's mini van power master, which has a 15/16 bore, but I would have to "modify" my pushrod to fit the piston.

Is there a master someone else used with their existing pushrod, or a combination of a master a pushrod from a different year car?

I have a 70 dart with SBP.

Thanks!