Arsenal CR Gas Block on MAK-90

[CGRifleman]

I want to replace the gas block on my MAK-90 with a CR-type so I can shorten the barrel and permanently mount a Blackout. Here's the gas block I was looking at:

https://www.k-var.com/shop/product.php?productid=17653

I know MAK-90s have a thicker barrel than Arsenals, so is it possible to have the barrel "turned down" to the right diameter? If so, how much could I expect a gunsmith to charge for this?