Black Jesus (from Italy) -
I've turned my stock 27.3" frame into a 27.75 simply by removing the buttcap, placing some kind of a spacer (in my case folded over lead tape and epoxy) at the end of the pallet, then secure the butt cap back in place again.
Even slight changes in length, change overall feel and SW of the frame dramatically. You can secure the buttcap in place temporarily with black electrical tape wrapped tightly, before you go about restapling or expoxying in the new position permanently. You might not like the frame you love now at an extended length. Having said that, you've mentioned you desire a higher swingweight... this might really work for you.
-Jack