I've had both the Crosswind and the Edelbrock Air Gap...they look very similar and the crosswind did seal fine for me BUT the Air Gap is so much better quality and doesn't make as many "cooling noises" when you shut the engine off.

I have some boneyard magnum heads that I pulled myself, and they're fine...not cracked. I will say that if you run nearly any cam that's not a stock cam you'll have to change the valvesprings. I also had to grind away some casting flash on the OEM heads for pushrod clearance. I use the Summit Racing (I believe they are made by comp or crane) 7.650" Chromemoly pushrods and they are much higher quality than the MP's. Stock rockers, old "LA" M/T Valve covers, and everything seals up great.