That is a picture of my current setup.  It's a 16" Bushy Ultralight in AWB compliance mode and has been 100% reliable thus far.  My problem is thus, I am wanting to either go to a 16" midlength or a 20" barrel but at this point in time, my budget wont allow for a completely new upper hence the rebarrel.  I also am planning to do an SBR upper for this rifle in the next year or two if the budget allows for it.

What I was thinking was to rebarrel the current upper and then later have the current barrel cut down and threaded for the SBR and build that upper at that point as money allows.  Would it be better that way or would it be better to just thread this barrel and put a FH on it and build the SBR upper from the ground up rather than cutting the current barrel?

Nice setup except for the no bayonet lug and FS.

The lowest cost option would be just to thread it and add your FS.

Next higher cost would be to change it to a mid length gas system barrel (with F type FSB and bayonet lug).

If you just rebarrel it now, just cut your old barrel later as an SBR and install it on a new flat top upper receiver.

Later on you'll have two uppers, a SBR and a middy then it's time to get another lower for the middy.

Black rifle disease can't be cured. LOL