I'm mainly interested in the heads. PM me with a price. Jim Butler Performance www.jbp-pontiac.com will steer you the right direction.

 

Definitely sell the HO heads and grab some $100 6X or 5C smogger heads. I ported my own 5C (same as 6X) heads using both the Pete McCarthy video and the new book by Jim Hand. Pretty easy to get 240-250 cfm out of the smogger heads. With the right cam, you can make 500 hp and nearly 600 ftlbs from the 455 with these heads. Stock crank is good for much more power than that. Most folks seem to crack the block before they break the crank (around 700-800 hp). I bought Crower sportsman rods and SRP pistons for my 455 but the power drops off around 5500 rpm so I could have just used the stock rods with the lightweight SRPs and saved $600. The 455 will take a lot of duration in stride and behave well on the street. My son's 455 idled nicely with the Comp XE284 with rhoads lifters and ran mid 7s in the 1/8th in a loaded 3800 lb '79 Z28. Plenty of other cams out there to choose from f or the 500 hp level. I'm using the new Tomahawk intake and a hydraulic roller cam for my engine. Should be right at 500hp/550trq.

New Intake

 

Some info on your HO heads...
71 455HO(LS-5) casting #197 intake 2.11" exhaust 1.77" chamber 111cc

The Casting number for your head should be on the head itself.
The 6X heads can be found on both 350's and 400's. On a 350 you will get a 6X -4 with a chamber size that is smaller(in the mid 90's cc), the 6X-8 was on the 400's and it has a chamber size of 101cc's. The 6X-4 was also found on some higher performance 400's. What kinda compression do you wanta run? That will dictate what 6X head you want.

Getting 500hp out of a Poncho 455 is not hard. You won't need to wind that engine up high to get that kinda power, there are build ups all over for what you're looking for. (I think car craft did one too..but there are a ton on the internet).
The number one decision you have to make though, is what heads you are going to use. After market heads will make your goal, literally, a cake walk...
Go with cast iron production heads, and you will have to work a little harder at it, but not too hard.
Again, it all depends on the head you wanta go with?

 

where do i find the casting numbers, on the top of the center exhaust ports? what cam would you reccomend using?

So basically, if i want to reach 500hp+ i need a pair of 6x heads which will have to be ported. . .

 

um yeah, after looking at aftermarket heads, they definately arent in the budget...

the 455 will bolt right up to a turbo 350 or 400 right?

 

yes

 

only if it has the BOP bellhousing pattern

 

Buick-Oldsmobile-Pontiac-Cadillac all have the same bellhousing bolt pattern and its different than the oddball Chevy pattern. The 2004r trans is a dual pattern and will fit both the Poncho and the Chevy. And give you overdrive as well.

Here is a pair of 5C heads like the ones I use. The codes are generally over the center exhaust ports. Going rate for a decent pair are $100-$300 depending on how fresh they are.

5C heads on ebay

BTW, I have a good BOP TH-400 trans in my garage. It has the extra thick case they used in the big cars (74 Granville). I had it converted to a short tail housing when it was rebuilt.

 

You can probably pick up a TH400 with a BOP pattern if you need a trans with one for pretty cheap.... infact I just gave one away last week for free to a guy who wanted to buy an engine block off me.

The casting number is on each head, clearly marked on top of the center two exhaust ports... (right beside or under the middle head bolt).

Do you want to go with a solid or hydraulic cam? A good solid one to go with would be Comp Cams 290B-6 with some 1.65:rockers... that should get you to your goal as long as your 6X's are ported and flow well, a larger 1.77 Exhaust valve will also help. You're going to need to get the heads to flow 240CFM or so to get the power you want.

 

what are the pros and cons of a solid or hydraulic cam?