Where can I buy a reliable remanufactured 318 for 1971 Duster?

I've never had an engine balanced.
Either 2 or 3 years ago I had all the machining done on a /6. Bored 0.020. crank polished std.
also had pistons pressed onto rods.
Block shot peened and magged. 0.030 off the deck. That was $400. Then I had the head shaved 0.070, seats machined for oversized valves, valve guide seal lands cut down, had it machined for actual exhaust valve seats, and bought them from the machine shop, they put "my". oversized valves in that I supplied/ assembled that head, , finished my home porting job for me. That was another $400. I didn't think that was bad at all.

Then, same machine shop. a year ago, I took in a single cylinder cast iron 12hp Kohler for a 0.010" rebore, valve job, cut the rod journal 0.010 under, deck the block (I think that was 0.010" too) as I couldn't get the head gasket to seal, replaced it 2x and it still leaked at that seam around the exhaust valve)
and that machine shop bill was $300. For a single cylinder Kohler!
Probably a year before the /6 work detailed above, I had (again) same shop do up a set of '302 small block heads- crack checked, complete valve job, 16 new valves, new guide seals, light mill (like 0.007") for a fresh sealing surface. And that whole Job with parts was $340.
So in all that single cylinder Kohler overhaul seems like a ripoff. Especially considering the last engine just like it at the same place yet again, done in between the /6 job and the '302 heads was 2/3 the price for the same amount of work.