Drum to Disc MC Issues

Oops, sorry guys, violated first rule of help requests! ‘68 Barracuda. I’ll edit my OP. There was no spring but there was a dust boot. I had a brand new in box early 90’s NAPA remanufactured drum/drum master identical to the one I just pulled that came with a new boot AND the little rod retainer rubber thingy which I had just ordered for ridiculous shipping cost.

So, can I just jam the rod into the master from the firewall side? Don’t want to unbolt that damn rod though. Should put a little silicone on it help it slide home?
The firewall has two sides.....but I assume you mean the interior side. Sure, lube the rubber retainer, start the push rod into the piston, start the master cylinder mounting nuts, tighten them evenly as you draw it up against the engine side of the firewall, and then push the rod into the master cylinder piston until it's fully seated..