I think you are on the right track.You can start by putting on a solenoid heat shield,and try a new AC Delco solenoid.They cost a little more,a differance of $10 maybe,but are usually better quality.This SHOULD solve your problem.
I say should ,because I went through this whole deal on my 67' this year.The car would not start sometimes after driving it.I put on 3 new solenoids( the third a Delco),2 types of heat shields,new Delco starter,ignition switch,horn relay,neutral saftey switch,cleaned every starting/ignition connection I could think of.It still left my wife stranded,final straw.I drove it down to Illinois where a highly recommended "guru" scratched has head over it for 8 days!Thank God he saw it as a challenge so I was only charged for about 1/3 of the actual time he spent on it.The price? Don't ask!I won't be putting to much $$ in it the rest of this season.
I hope you have better luck then me!I say a prayer now before I turn the key,I still don't trust it.
67 RS RAGTOP # matching
4X4 Chevy truck