The dual pattern 4150 is a good idea but you have to make sure it seals up all the way around. Some 4500 intakes are opened up too far for the 4150 base plate. I used to make a 1/2 inch adapter that sealed a 4150 dual pattern carb to a 4500 intake. It had 7 degree taper in the bores and anti-reversion lip on the backside. It worked really well but not very people were interested in it so I stopped making them.
That's a shame it's a really cool piece , do you have any left I'll take one!
