OK- having been down this road - and having had the modified engines and having setem up with pipes etc-- here is my two bits worth -
they can be made to run - BUT just go buy a ZDZ60 - all in all cheaper and you will never get the power from the Tartan you get with a good 40-50 60 gas. also the 60 is very smooth - no problems on this 17 lb model.
this Tartan engine is about the weight of the 50 -60 class engines
We setup a TOC model in 90- with one of these - well modified -on pipes - it was flown to 2nd place by S Rojecki- I have one of the models - (I designed/ built them) still- but now with a ZDZ60 - and the power is much greater -
originally the Tartans turned about 9000 on 19x10 carfully shaped Max Daly props -
now I use a 24x10 MenzS or Mejzlic - rpms from 6000-7000 much beter recovery power .