Take the 20 pound weight penalty and get a Optima battery, that what I'm doing, forget that small lightweight battery crap, either they are big time expensive and most of the time have no guts. If you're running without a alternator, most do, then you need a good battery with a good reserve.
Tony read what I said on the Spridget forum at MGEX about lightening cars for racing, some places our cars need to be lightened, someplace they do not need to be. Like the way you wittled down your front hubs, that worries me, if you crack one in a highspeed corner we could be dragging you out of that car, not anything any of us want to see happen. Be smart when it comes to lightening stuff. You're not only responsible for yourself out there, but the rest of us as well. A amatuer race car needs to be sturdy and well built, this is not F1 where we can afford to replace ultralight items after each race. If you take turn 5 correctly at speed, which IMHO, most vintage racers do not, you going to be smacking the curbing pretty good each lap, and this takes it toll on spindles and hubs on the right front, I crack check my RF spindles after every race at Road Atlanta. Food for thought.
As far as the angles of the shoulder and lap belts, this is big time important, there should have been paperwork with your harness explaining this, if you don't have it I believe it can printed off the Simpson site, follow those instruction closely, improper angles on your belts can cause the harness to not do it's job if needed.
When it comes to saftey using the modern SCCA GCR is a good rule of thumb and will supercede all old GCR rules and still be legal in vintage, personaly I think vintage needs to take safety more seriously, vintage in the past decade has killed more people than the SCCA.