['68OrangeSunshine]

You could -- if desperate enough -- drill 1'' holes in the doghouse alcove (?) for the pushrods to have more headroom, but you'd probably cause big problems in the underdash anatomy, not to mention sealing issues.
Another alternative might be to disconnect the driveline at the transmission [SM465], loosen mounts there, dismount the engine at its mounts and allow the engine to be lowered in the front. This would require releasing all radiator hose connections, possibly pulling the fan, fuel line, etc. More trouble than it's worth. I think I did it as RichardJ describes. It was a long time ago. [late '70s, early '80s, ICRS] Since then I try to overbuild the head when the whole block is out, to prevent failures.