Ok, that sounds like it might be enough.
And, I got a confirmation from an IP-036 owner on another forum that 73mm is about what it is.

With so many 27.5+ commercial frames coming out with boost spacing, i think its only a matter of 6 months before we see a chiner.
I might just wait it out..

I've done quite alot of searching on line, and all I've come up with is that the IP-036 has about 73mm of spacing where at 27.5+ tire would need its clearance.  That is very, very tight.  Much tighter than my 2010 SJ FSR 29er, which i measured at about 82mm!

It seems that the cm-036, ip-036, fm-o36 frames have tighter chainstay spacing than most 29ers.

Bummer, unless somebody has a real setup to report, then I'll wait for a boost 148mm 29er FS carbon setup.

Hi All, 

Looking into the possibility of getting a 29er FS frame and running the WTB trailblazer 27.5x2.8 tires.
However, I am worried it may be too tight.
Anybody try it?

I think the right prototype would be a Trek Fuel EX, which has short chainstays and wider boost spacing for the 27.5 plus tires.
There are several name brand frames out there, but we are talking $3000+ for the frame alone.
So, I am thinking to get the 29er FS as a stopgap measure until official 27.5+ bikes are available from Peter or others.

Any thoughts?