At 20:08 13 August 2019, JS wrote:
Regarding mods, the eTug deserves mention.
A Pawnee with a 350 cubic inch Chevy LS1 running on Mogas. Early
experiments provided too steep a climb angle, so the original 4-blade
prop
was adjusted to decrease the climb rate. Now it has a different prop.
I've hooked many gliders up to eTug, yet to tow behind it.

https://www.glidingclub.org.au/membe...aircraft/etug/

These days a crate LS3 engine can be purchased for about $8000 and
produces
430HP on Mogas. Car engines require a PSRU (speed reduction).

https://www.gmperformancemotor.com/parts/19370416.html?
gclid=Cj0KCQjwv8nqBRDGARIsAHfR9wC30A7wF3SFSrhYOBoL dkinr_7M
GZMpHxignUEhA1qfW5iBSSEbHwAaAhPlEALw_wcB

Not much concern about shock cooling or leaded Avgas going away.
Jim

A Zlin Z-137t would seam to do the job. This is turbine powered and
there is a video on U tube of one towing 9 x L13 Blanics in one tow.