Handguard to barrel length

[StillServing]

for my SBR build, I'm getting a 9 inch barrel and want the handguard to come up even with the tip of my YHM phantom QD with the can off so when I put the can on, the joint, if you will, is hidden just inside the handguard.
Can anyone give me guidance on what Handguard length I should be looking at or is this just going to require some custom fitting later on after its all built up

 

[DarthZed]

I'd wait till you get it built, them measure for an exact fit. Easier and more accurate than estimating. JMO