pre and post improved cooling heads

[FLY4SCOUT <FLY4SCOUT@domain.elided>]

A week ago I took my 392E t'all donor motor (for a Scout II) to the machine
shop for a rebuild.  After pacing all week like an expectant father, I finally
heard the news.

The good news was that the block, crank, and rods were all healthy. 

The bad news was that both heads were cracked (like father like son).  I spent
half the day looking for a set of improved cooling heads in the local Phoenix
junk yards, and only found one set.  That one set was on an engine the place
would not part out.  I did find 5 sets of pre-improved cooling heads.  This
got me thinking:

Would the older heads work on my improved cooling engine if I put freeze plugs
in the holes that normally had the water jackets in it and used the improved
cooling head gasket?  The heads look the same, except my heads had the freeze
plug in it where the water jackets would be on the older style.

 I know the head gasket is different between the pre and post improved cooling
engines, but is the difference because of a change to the block and not to the
heads?  During disassembly, I noticed the head gasket sealed off several
openings in the heads to prevent flow into the block ( some places in the
block didn't even have openings that would have matched the openings in the
heads).  As a cost saving measure, did IH ONLY change the blocks and the head
gaskets (and not the heads) to redirect engine coolant for better cooling?  If
there is a difference in the heads (requiring new castings), why did IH leave
in the openings for the old water jacket inputs that now require freeze plugs?

To further tease my brain, I thought that if that would work, why not use a
set of 345 heads, add the freeze plugs, and use the IMPROVED cooling head
gasket to provide for proper coolant flow? 

Has this idea already been discussed?  The health of my long awaited child
depends on a speedy response from all you specialists in the field.

Thanks,

Mike
FLY4SCOUT@domain.elided