My install was a lot easier in that the core support and valences were not in place at the time I reinstalled my engine and transmission as a unit - front end of the car was "wide open". However, I would definitely recommend using a "load leveler" or "tilter" in any event - a "required tool for the job" - for multiple reasons, including safety. They are not expensive and are readily available from many sources, including Harbor Freight - about $25. (Local store or on line.)
I would also definitely recommend not having the distributor in the engine at the time you install the engine. Don't want to break it as you maneuver the engine and tranny into the car. As a matter of preference, I secured the chains at the exh manifolds instead of using a carb plate. Only problem with this setup is that you have to protect the corners of the valve covers. In the attached pic, the engine and tranny are ready to install into my '69 RS. Auto trans cooling lines are also installed. Since mine went in without the core support in the car, and I did not use a carb plate, the carb, water pump and alternator have already been installed. Only accessory that went on after the install was the distributor. I used an old set of valve covers for the install and swapped them out with my "pretty" ones after the engine was in. Starter, fuel pump, and stock exh. manifolds were not an issue.
However, as CNorton suggested, with the core support, valences, etc still installed, give yourself extra room by installing the water pump and alternator after the engine is in the car.
As John indicated, use grade 8 bolts with enough flat washers to ensure that nothing will slip through the links of the chain.