383 or 455 1979 pontiac firebird t-top

i have a 1979 pontiac firebird t-top and im needing to know if i should put a 383 or a 455 in it...and what is the big difference between proformance?  

Is the 383 a chevy engine or a true Pontiac engine.
The 455 is a true Pontiac engine right?  
Professonal hi-performance engine builder

horsepower sells engines and torque wins races

so now I'm curious...how do you make an original 383 cid Pontiac?  Their 350 already has a 3.75" stroke, and the bore won't go out to 4", will it?  

cough it up pontiac4...not calling bs here...more interested in the method to the madness
can it be stroked further?
i'm a sucker (sorta) for the road less traveled  

A Pontiac 350 bored .030 over and they use a 4.00" stroke which is basically and 428 crank that has 3.00" mains instead of 3.25" mains there are a couple of Pontiac parts places that sell these rotating assemblies to convert a 350 Pontiac into a 383 stroker but the dyno test results were not that impressive for the 383 pontiac for it to be worth the extra 1500 dollars and I have seen more power pulled from a Pontiac 350 using the stock configuration stock stroke crank.
Never count the Pontiac 350 out it can be built to be a potent performer.  
Professonal hi-performance engine builder

horsepower sells engines and torque wins races

i haven't heard of people stroking the pontiac 350...i take it from what you (pontiac4) said that it isn't popular due to cost/gain ratio...

do the unimpressive gains stem from bore size/valve size restrictions/shrouding in this application?

just curious now that the subject (pontiac 383) has been brought up  

Most people probably have not heard of stroking a Pontiac 350 because there too busy downing the 350 and building a 455 mostly due to lack of Pontiac knowledge and how to pull power out of one a 350 pontiac that is.  
Professonal hi-performance engine builder

horsepower sells engines and torque wins races

Actually, I had read about the 383 Pontiac, then forgot all about it until you explained it, b/c the idea of finding a 428 crank--much less wasting such a valuable engine to take that one part--was like landing a unicorn.  Doing a welded stroker seems closer to reality.

But still, the 350P has a bore and stroke similiar to an LS1 Gen 3 Chevy, 14 degree angle valves, 6" long connecting rods, an "air gap" style intake long before Edelbrock thought it up...the weak spots are those cast iron connecting rods (go use aftermarket or Chevy BB rods), lifter bores that need to be braced or supported or an aggressive cam will snap them off the side of the lifter valley, and they aren't a Y type or deep skirt style block, like the LS1 or Ford's FE or the Hemi or the 4.6 mods.

If you can figure how to run a cathedral style head port to push air into a small bore, long stroke engine like most 4 cylinder and new V8s are designed...you can engineer something fun out of the 350.  But everyone's gonna believe its a 400 instead, since the blocks are all the same like AMC's.

I'd love to see an article on one of these, but for magazines...if you can't bolt it onto an engine, it must not be a possible hot rod trick.  

There was a article that CC did on a Pontiac 350 and B. Fulper got 670HP with a 125 shot of N.O.S.  
Professonal hi-performance engine builder

horsepower sells engines and torque wins races

That cheap china made intake they call the tomahawk/hurricane did not help any it is probably why they did not get more power form the engine.  
Professonal hi-performance engine builder

horsepower sells engines and torque wins races

Forget the 350!!
Build the 455 for pete's sake!
It sounds like it might be cheaper if I follow the threads right.
You won't regret the performance of the 455. -That's my vote!