I do not foresee running an event. But if I did it would be limited to Cox reed valve engines in the spirit of Walter A Musciano and the genuine Scientific hollow log.
Many of the Musiciano Scientific plans show .049 OK Cubs, later showed the Cox .049 reedies with tank. I think it would be fairer to say that sport engines must be used, which as per current rules eliminates Tee Dees, Killer Bee reedies, etc. I think it should not include Medallions. However, I think it would be fair to include the Cox .020 Tee Dee, as power is sport .049 like. The OK Cubs are not that powerful, hence why Cox with their better power although reed valve and cheaper manufacturing techniques with high quality dominated the sport flier market. The Wen Mac and McCoy .049's were also sport like, akin to a Cox Babe Bee.
Reason why I mention the Gilbert .074, is that it is an era engine, and it's power is akin to a reed valve .049. Many of Walt's plans state for .020 - .074, some .020 - .099, for some of the earlier lame powered .099's. (The Fox Rocket .09 comes to mind, although it is tad but not much more powerful and beyond reason to include in this discussion.)
Retaining sport engines keeps it a fun flying event eligible for all to attend. Regarding external fuel tank, these are easy to add and make it work with the Musciano kits. Some kits of the 1960's came with a balsa block to allow Cox .020 Pee Wee to be mounted within the cowling, which would also with trimming be a suitable spacer for shorter tankless engines. Some of the kit marketing photos and box art show a tankless engine on front like one of the OK Cubs, for example, Li'l Devil. (Can't remember off-hand, there was "A" and "B", one had a tank, the other didn't.)
It's all in fun, and to see what modeling was like 50 - 60 years ago. Anyway, that is my personal opinion, for what it is worth. And personally I wouldn't mind seeing the event expanded to Walt's 1/2-A profile models as well as built up fuselage. Back 50 - 60 years ago, to me they were different building techniques, but of the same class, because after all they were all or nearly all were Walt Musicano designs.