carb size for mini blower

What is the Compression Ratio?
That cam has a 110° LSA, typically you'd want a wide LSA around 112 to 114. If your CR is high (10:1) then the xe284 will bleed off boost.
No need for a boost referenced regulator.
I run a Holley HP 950 boost referenced carb on my 174 blown 360, but I spin the engine way up in RPMs.
Find out what size blower it actually is before purchasing a carb.