Replace the VMAR firewall with 1/4" - 3/8" aircraft ply (more weight, better longevity)
Replace the plastic motor mount with a metal one (more weight)
Replace the plastic spinner with a True Turn (more weight)
Replace the lightweight nose wheel with a solid DuBro (or similar) wheel (more weight)
Move the servos forward if you can
Put in a bigger NiCad battery pack (2000 mah)
Make up a lead slurry (lead shot and epoxy) and pour it into the front lip of the cowl (more weight further forward) Ensure you don't shut off any air access

That should save you some weight in dead lead

Don