This is one place where you can buy high quality fiberglass repair "stuff". They have pretty much everything. Make sure you buy resin that is compatible with fiberglass and/or SMC. Your '72 should be fiberglass, not SMC - I "think" SMC started around '73 ???
www.uscomposites.com
As mentioned, chamfer the holes with a countersink both sides if accessable and use some epoxy paste such as this. No need for mat for small holes.
This stuff is used to plug screw holes of yachts under the water line.
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