It is a fair amount of work to remove and reinstall the fedders. If it is the OE unit it is almost 3 decades old. Might want to keep that in mind. If you want a hard start I have used the Supco SPP4E on LG8000 btu window unit with the OK of the AC forum guys. I am sure it would be fine with the Fedders.
The Micro Air may be a better choice depending on what you are trying to accomplish. From my reading I suspect that RT installed a hard start on their AC units, not sure on that but a few people have reported having one.
Might want to post why you want to add starting assistance to get better input. Is it to use a portable generator?