If you want to widen the fuse, why not just make the firewall proportionally larger, and extend the length proportionally longer? You are going to have more frontal area anyway and will need room on the firewall for a larger engine. I would think that, that would take care of the bending issues.
See N64KR at http://KRBuilder.org - Then click on the pics See you at the 2009 - KR Gathering in Mt. Vernon, Ill There is a time for building and a time for FLYING and the time for Flying has begun. Daniel R. Heath - Lexington, SC