Bobzilla said

Drilling and tapping existing heads for the LA pattern is the way to go to open up manifold selection options. If you're very careful and seal off the valley area with lots of shop towels you can drill them on an assembled engine too.
With the cost and availability these days of the M1 with injection bosses, you'd be saving money by drilling the heads and using one of the LA intakes even if you have to add bosses to a non-injection intake like the Victor 340 subcom is running. This leaves the M1 available for trucks, although most trucks can just use the Hughes air gap.
There is also a single plane with injection bosses cast in and Magnum vertical mounting bolts available from Indy cylinder head. I think it's 360-M. Only problem there is the plenum is really tall so you have a little extra into having that machined off.

Click to expand...