I missed those carbon film resistors on the plates of V1A and V1B. Those will affect the sound of the amp a lot even if they’re the correct value. I assume the originals had drifted too much.I'll just recap what glpg80 already pointed out. The original .68uf Mustard has been replaced with some type of polypropylene cap from the looks of it. The 100K plate resistors on V1A V1B have been replaced with modern CF resistors. In 1972 the V1B coupling cap usually was a strange long pencil like metal electrolytic at least it was on my 72 50 watter but the NOS Mustard there is an upgrade. The V1A 330uf cap looks like it might still be an original Erie it might be fine or ready to leak electrolyte just check it out mine was bad so I changed it out for new.
The Bias filter caps are newer that's good, the PI couple caps are some type or orange drop could be either polyester or polypropylene 715 and they look like .047uf which is actually good for a 50 watter on the low end. I installed .1uf in mine and it's fine.
The Yellow rectangular plastic looking chicklet caps were common in the 1972 year, mine has them as well.
The green electolytics of the far right of the board a just there to make sure there is no loud click when coming off of standy, if they are original you might want to upgrade them with two .22uf 1000VDC polyester or polpropylene caps. If the amps been played regularly then they might be fine.
The amp looks nice a clean with up to date maintenence, it probably sounds great the way it is.