well that depends on the converter. if its some 99 dollar special with 80's technology then yes they will hate it. a very efficient modern converter is awesome.
newer engine as in what? modern hemi? big job and can be pricey too. why not redo the 318 or stick a nice running 360 in it. being its already got a small block in it would make it the cheapest route.
depends what you want.
if you are going to put the a/c back on then atleast hang the compressor and get the pulleys and belt routing correct.
if you don't plan on putting the a/c back on then get the proper non-a/c pulleys and brackets.
I'm sure the alt. did not come with brackets.
what I'm saying is that motor has air conditioning pulleys on it. its why the belt is riding on the front pulley of the alt. the belts are also routed wrong.
if the new alt only has a single pulley as pictured then the belt will not line...
hell, years ago when i had a very stock 360 choked down with 273 manifolds in my 64 valiant it would out run a certian 70 hemi charger. he was running mid 14's and i was running low 14's...:)