The engine in your photo is set up for a bypass type oil filter, so that problem should be solved already. You'll need a 216 style water pump- - - -not sure if the one off your early style 235 will fit or not. The adapter plate allows the shorter pump with the higher mounting position to clear the radiator, and also aligns the fan vertically correctly with the 46 radiator. The 46 bellhousing, clutch, and flywheel should be a bolt-on swap to the 261. If you're still running the non-synchronized "crash box" transmission, be aware that the 261 will have a lot more torque than it's designed to handle, so don't get frisky and do any burnouts with your new-found power!
Jerry

Edit: The stand that engine is mounted on with the engine projecting past the front wheels is a disaster waiting to happen- - - - -please add some kind of support to the front to keep it from tipping over forward.

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!