I think you would be fine with 55 amps. If not just reinstall the GM unit and sell the Denso. Have you considered a lightweight battery? The FX guys would've killed to have a 6 lb alternator that put out 55 amps and a lithium battery. If you could go back in time and show those guys this stuff they would burn you for witchcraft.

Do you use CAD for any of these parts? If you have access to a simple CAD system then you can easily get blanks cut from aluminum or Ti on a water jet or on a laser. I paid $99 for a set of MasterCAM Design years ago and it is all I need to design my parts.

Have you looked at the super lightweight gauges that are available now? The new Holley EFI gauges only weigh 2 oz each. Old school Autometer gauges are 6x times heavier than that.