Vintage 1964 Volkswagen Bus, New Stereo System

I have a 1964 vw bus I want to install a brand new stereo system. All this Items are not installed yet. Head unit is a Retro sound long beach. Frt n Rear rca pre amp out puts Front and rear speakers are Alpine R-s65c 300w peak 100w rms Using an Alpine amp MRV-f300 50 watts RMS x 4 at 4 ohms (75 watts RMS x 4 at 2 ohms) 1st question Is this Amp enough to power the Alpine speakers? Or am I under powering them? 2nd If any one is familiar with these buses should I mount them on doors or buy pods and have them front mounted towards me? Rear speaker are going to be installed on the rear upper deck of bus. For a sub I have the Alpine mono MRP-M500. I do not have a sub yet. I do want a good quality sub, just not sure which one yet. Any suggestions would be GREATLY appreciated.

1) That amp will be plenty. 2) I'm not familiar with those. 3) Give a listen to some subs at a local shop and buy what sounds good to you.My ex once told me I have a perfect face for radio.