Port timing

Snagged a 3 cyl. OMC w/ 15" mid for my next project. Does any one have a port map from the mod 50 days. Before I design a port map I would like to have something to compare it to. The powerhead is actually a 56 ci motor. The adapter plate was modified. Thanks.

The porting is only part of the picture

To make it work, you need the pistons, head, front end & carbs

I beleive that the Ex. opens at 90deg from top and the In. opens at 120deg.