Yes, see if that combo bolt is in the lower bypass cover for sure. That dark green color was only used for a few years, so most likely a Johnson 20/25hp from 69-70. I would not split the block apart just to look at the recirculation system, unless the powerhead is damaged and needs rebuilding.
I don’t think it is a 71 model (a good thing), because your powerhead doesn’t have the nipple in the upper bypass cover. 68 models seem to show the fuel pump on the top bypass cover (might just be a mistake in the picture though). 71 brought the completely drainless recirc system which resulted in degraded idle quality, and some plug fouling issues.
Now to determine whether it is a 20 or 25hp model…. There were many subtle differences in these two models, it will take some more in depth investigation to make this determination.
