Will pontiac 301 heads bolt on to a 400?

[Stacy]

Hi I am restoring a 1981 Pontiac firebird formulat 4.9 turbo i was planing on using the origonal turbo system air plenum carb headers manafold and turbo charger but the 4.9L 301 has a busted timing chain turned main bearing a few cracks in the crank and a cracked conecting rod so I decided to use my 73 HO Pontiac 400 I had sitting around only one problem there's an inch of space on each side of the 301 manafold between the heads of the 400 not to mention the head ports are totaly different the only solution I can see now is to try and take the heads from the 301 and put them on the 400 but I don't know if the heads will fit so rather than dis asemble a perfectly good 400 just to find out it won't work I'm trying to find out if my heads and manafold of of a 1981 301 v8 will fil on my 1973 400 any answers will be much apriciated thank you