I have started problem solving the issues I had coming home based of previous threads I have read on here. Driving home the truck would buck and completely give out on me on the way home. I tried downshifting, I tried less gas, more gas, you name it. The PO said it would lose power around 45 mph and seeing how it had an old Mikuni Carb I assumed that had something to do with it. PO also said the person before had "rebuilt" the engine and looking at the belts and hoses they do appear to be newer and in good working order. PO pointed out that there were two fuel pumps, one electric that is not hooked to the battery and a manual pump. At this point I have got a new fuel filter to put on and I am looking into switching out the carb, but on closer inspection I noticed the engine head only has one bolt keeping it attached to the block. So I have the following questions.

1. What size/type bolt do I need so I can replace the missing bolts.
2. I have seen some Weber 32/36 on facebook mrktplace for $150 vs the weber 38 for 500. Is it worth going this route to save some money for now? I am going to want to do an engine swap one day so I am not lookin to dump a ton of money into this one.
3. 1st and 2nd gear seem to "off" if you move the stick all the way left and up or down it does not go into any gear, if you then push the stick moderately right and then up or down you can find the gear. Any suggestions on the cause and how to correct this?