The hard part, of course, will be finding someone to produce said washers for you....cutting a washer on a slight angle, accurately, is tougher than it sounds.
Actually there are a few producers of both the square and round taper cut washers in various angles, so if I can calculate the angle, I'm hoping I an luch into something within a degree of perfect.
The aluminum paint job is the powdercoat the former owner had done (I was sceptical but its growing on me in terms of both looks and durability)- that D-66 I can actually use as is now that I know that the angle is correct for all 66 and up LA motors. Now I'm trying to figure out how to make my D-64 more useful by using the right washers - IMHO getting the angle right through machining (or even worse - grinding) seems to be a fools errand given each of these surfaces are down in odd shaped recesses in the manifold...