sounds great, ga16de are easy to find at any wreckers these days.
I believe you best design a cast iron turbo manifold first for
the A series to get some cash as plenty of peeps would love one.
eg.http://www.ebay.com.au/itm/Cast-Turbo ... ories&hash=item5d2e972d18
Otherwise a 2 piece alloy block to suit the ga16de head straight off and
also accept a ca18de box bolt up pattern would be much more effective
as there are too few 5 speeds for the A series and to do the timing case
and eliminate the pushrods requires quite some work.
separate cylinder casing
Best would be to make a 2 piece block to accept a zx9r head
using e15et crank or other e series crank as the zx9r is a
75mm bore engine and similar to E series spacing.
eg.http://www.ebay.com.au/itm/Complete-C ... Parts&hash=item3a7370ba1e