? about using GT40 bolt down rocker heads on an early smallblock?

Looking for some thoughts here:

I was going to use my Ported '65 C5AE 289 heads with 1.94/1.60 valves and 54.5cc chambers with my '68 302 shortblock. I am now trying to decide whether to go with a 347 stroker kit, but I calculate that it will be around 11:1 CR if I use the 54.5 cc chamber heads and flat top pistons. Plus I know I would be somewhat limited with airflow and these ported heads. Guess I could sell them.

I have some used Aluminum GT40 (non-x) heads that I was going to use on my '94 Cobra with 64cc chambers. They are setup for bolt down rockers and would need to be converted to screw in studs/guideplates. Shop said it would be about $150 to convert the heads to screw in studs with guideplates. I have some used crane gold 1.6 roller rockers. Or would it be possible to use bolt down rockers with the setup? I have hardend 6.875" length pushrods. I'm assuming I would also need different pushrods since the lengths would be different?

Thanks,
Jon

[addsig]

I don't think the bolt down rockers will fit because of the rails at the tip of the rocker that keep them lined up with the valve tip, they will not clear the valve springs. I had this same problem when I changed to a set of worked 351 heads. I would go with the crane rollers.