You do not want to use the head as a drilling fixture ???------There is a reason shops say -----NO -------It usually takes too long to set up and do the work.------It would be far cheaper to find a used block / parts motor.-----Shops do not need a customer howling at the cost of a 5 minute (...
The bulb is a manual fuel pump.----If operation of motor does not change when operating it then I would say it is not a fuel supply problem.----Some simple trouble shooting must be done.
Use the material you like.-----I use composite ( hollow ) hockey sticks / carbon fiber / west system epoxy.----Ultra strong and will never rot.-------You should use a plate for motor clamp screws so they do not dig into the wood.
Remove the transom caps on the corners.----Remove that channel.----Remove that piece of junk plywood.-----Install new plywood or a composite material.-----Should be easy to do.
Test run with a another fuel tank and hose.----Because of the shudder have a look at the gear oil.----Test run with a timing light one cylinder at a time.
It is said to be a 1998 model.-----They did not market the 3 cylinder 35 HP in 1988 !!!-----They generally do not have an overheat warning light.----Some models have a warning light for low oil level in the " less than reliable " oil mixer unit.
Do a complete evaluation of this motor before spending your beer tokens.------On those models 9 out of 10 have needed a new water pump impeller.----At least on my work bench.----Compression test first !
Model # of your motor ?-------Temperature light ?-----Is the " mickey mouse " oil mixer still in service ?-----Or running at 50:1 mix ?-----Do a compression test first !
