[Old Tele man]

...well, here's my "DIM LIT LIGHT BULB" idea submission:

...how about selectively dumping the exhaust through a portion of the radiator to speed-up coolant temperature-rise and thus initial engine warm-up.

...maybe a thermostatic "dump" value (like the old exhaust "rattler" used to 'crossover' the exhaust through the bottom of the carburated intake manifolds).

...sends 'some/most' of the exhaust thru the small radiator when COLD, but once reaching operating temp then sends 'all' exhaust through regular exhaust system as normal.