The engine isn't a #s unit, so preserving its originality really isn't a must. There's also a filling station close that sells 110 leaded race fuel. By my calculation, a 4:1 mix with oxy free 91 puts me at 94.8 octane. Not enough lead for the valve seats, but some is better than none. As the roller vs. flat tappet debate, I've heard the pros and cons from both sides. I do run Brad Penn oil, so I know about that part of it. I'm in the information gathering stage for this future endeavor, so nothing is happening to this engine at the moment as it runs like a Swiss watch. Just would like a little more power for the butt dyno and the smile factor.