MoparGal (Alexis B’s) 1975 Plymouth Duster Build
How is the other engine?
Would a rebuild be in order?
A Junk yard 5.2/5.9 is an excellent option. I did one in my ‘79 Magnum with the simple bolt on parts. RPM intake, (though a speed master is cheaper and just fine for a daily stock driven engine or mild performance)
Carb, MP ignition package, headers into dual 2-1/2 exhaust.
The 5.9 done this way is an easy 300hp. It’ll make power until 4500 and fall off. I’m not sure what the 5.2 will make for HP though.