How close is Crystal 80 and 120 to Crystal 75 and 150 respectively?

Doing a 'Can You Brew it' Clone and trying to decide how off I'm gonna be on the clone if I don't order in the special british Crystals...

i'm certainly no expert on crystal malts, but i would guess you could sub special b for the 150 (with some flavor consequences of course, but it will still make a good beer), and i'm sure crystal 80 would do just fine as a sub for 75. if all you have is the 120, again, i'm sure that'll work well also.

which beer are you brewing?

edit: just saw you did the terrapin ryePA, i did that one also, the keg is almost gone. nice beer.

I'm curious as to what you're brewing too.

I just brewed the CYBI Stone 2009 Old Guardian clone this past weekend. Went very well. Thinking about doing the Terrapin Rye Pale clone too. Also brewed the Oskar Blues Gordon clone recipe and it's really awesome.

A couple thoughts for you:

Different crystal malts contribute different flavors, so substituting different crystal malts, so adjusting the color will still give you some different flavors in your beer.

You can turn regular old 2 row into whatever crystal you need by soaking the grains overnight and baking them in your oven.