Remarkable that folks will tip the bar tender , first day on the job.---Rarely tipped the gas station attendant out in the rain or snow filling your tank.----Or tip a grey haired ,mechanic with 40 years experience taking care of a $100,000 boat.
Most Johnson / Evinrude motors from the 1950's through 90's can be converted to long shaft.----And many " sail models " left factory with a 10" extension.
Need to review your parts books.----That exhaust housing was used from about 1954 to 1979 on the 5.5 / 6 / 7.5 HP -----Just looked at a 54 and a 79 in my parts shed.-----No plate on them !!
That missing bolt does not cause compression issues in the crankcase.---And it cannot cause fuel to leak elsewhere in my opinion.----Find the real issue.
Just install a helicoil and do not worry about the wee tab.-----The hole does NOT go into the crankcase.---Just checked.----And it would not cause a loss in performance.---I would say do some trouble shooting and do not run the motor until you sort this out.
The 6 has needle bearings on the crank journals for the rods.----Run on 50:1 mix.----The 7.5 was marketed for 56 / 57 / 58 and they are a great running engine as well and run on 24 :1 mix.----The 7.5 has the slip clutch in the gearcase and better bushing above the pinion.
That hole may go straight into the #1 crankcase.--I can confirm later when looking at a block.-----You are loosing crankcase compression and suction. -----Do not run this motor until you sort it out.
Post pictures of the cowling.----Start with a compression test on that crossflow !----Post the values here.----These motors are famous for broken rings.-----Motor is 1988 to 94 vintage.----Most parts are the same every year.
