Hi

Fiberglass is usually heaver I hear, prone to be tail heavier requiring "possibly" 3x the amount of lead need upfront to counter balance...but that is a general statement not one on the P51 Ziroli fiberglass fuse. Also you need to watch what type of glues you use, clean the fiberglass properly before gluing, make sure there is no resin wax build while you sand etc.

In my build forum in the previous link there is guy who posted some pics of his P51 with flitemetal covering...that was fiberglass fuse...maybe search him out and email him directly...don't recall his name though right now.

Matt