Technical Help required with GMC head gasket please

Hello everyone.
I am in need of some help, please. I am trying to put a 46-54 270cid GMC motor (according to casting numbers) back together in my sprint car. This motor has been heavily hopped up in the past and so is now far from stock.
I have a new gasket set, but the bores are larger than stock (approx 3.15/16"). The head gasket in the kit I have is too small and overhangs the bores. I am worried about hot spots and detonation with the gasket hanging into the top of the bores.
There is a part number on the old gasket (Felpro 7607), but I cannot find any leads on where I can get one from, nor what I can cross reference it with.
Please can any of you experienced guys give me some guidance on this - I am hoping to get to the beach races with the car in May.
I am in the UK, which makes it even more complicated!
Thank you
LT

 

Best gasket company makes 302 head gaskets, but won't sell to individuals, only businesses. Find a shop that will order one for you.

 

Thank you I will check them out. Is the 302 head gasket the same as the 270, apart from bore diamter?

 

LT, also check out another Hamb member, Countn' Carbs here on this site. He lives in Colorado and has a
thread that started some time ago, but he has nothing but high performance Jimmy's. He might be able to
offer you some info. for a head gasket or more insight. Good luck, Bob

Projects - K-88 Dragster / 6 Cylinder | The H.A.M.B. (jalopyjournal.com)

 

I have nothing to add, but that sure looks like a gas to drive.

 

Look on the Best site. Their 302 head set will have all you need and their intake manifold gasket is better than anyone else’s. A 3-15/16 bore is close to the limit on the later blocks but good on the early ones. If your H head has not been cut too much the compression is pretty good. I’ve used Venolia pistons that look like those on a head with .100” cut off. The H head accepts 1.94-1.60 Chevrolet valves with ease. I’ve also gone to head studs from ARP. They don’t list them but you can buy them by length.
Looks like a lot of fun.

 

I got mine from Egge Machine. Engine Rebuilding Set – w/Graph***eHead Gasket – Egge Machine Company

 

The Rockauto Felpro gasket is on Wholesaler Closeout, so might be gone soon.
They are cheap enough, at £10.02 each, but an additional £30 for shipping & fees. However it's the same shipping cost for three of them, you could order a lifetime supply!

 

Thanks guys. Roy at Best Gaskets and Bob at Marx Parts have been really helpful and I think I am now sorted.

Here is a short video from when we got the car started a couple of weeks ago.

 

Is this the same car?

 

Since this thread has been revived, I checked Rockauto again.
They have the gasket back in stock, but now it's £25.65! Two and a half times as expensive.
It's .058 to .068 ins. thick, so nominally 1/16.

 

Everything is up. Bests are still the best especially if you’ve added compression.

 

It's not - the frame and axles are different a**** other things. Thanks for sharing it though.
LT

 

Good news, I figured out years ago that If you ask the manufacture who to buy a part from when they won't sell direct to a retail customer (I have no issue with that) that you normally get the sales outlet that they are comfortable in dealing with. Sometimes it takes a couple of steps because there may be a distributor in the middle.

The car sounds great, glad you got it all sorted out.