G’day MonteNZ,
The Trojan engine fitted to the Seacraft Tornado is not too dissimilar to may of small engines of that era. The spark plug enters at the center of the head, therefore finding TDC is as simple as removing the spark plug, holding a pencil or similar against the top of the piston and rotating the crank until the piston is in its outermost position. I say outermost only because the head is arranged horizontally. All other tips that Garry has provided are valid and should help you with the timing.
Be aware however that the Trojan engine fitted to the tornado is not the same as the Trojan Mini-motor as used on Cycles. The Tornado has a 75cc engine, whereas the capacity of the Mini-motor is only 49cc. This motor also has a slightly different fuel and exhaust arrangement, hence the timing information (even if clear) may not have been transferable to the Tornado outboard anyway.
Just to close off, for those who have not yet seen a Seacraft Tornado, following pics are of the latest model with underwater exhaust. As said by MonteNZ, they were originally built by Seacraft in the late 50’s and early 60’s. Seacraft was located in Mordialloc, Victoria, Australia which is approx. 2 mile from where I currently live.
Seacraft history here: http://www.seacraftskiboats.com/index.html
Regards,
Spiro