What to do with Canon FD 300mm f2.8L?

Seeking advice and opinions. I own a Canon FD 300mm f2.8L which I love and have used for many years. This lens was the reason I stalled and stalled before finally purchasing my 300mm Pro. As 300mm Pro owners would understand it has become my favourite lens by a huge margin and I rarely use the FD lens now.

So I'm seeking advice on what you would do with this lens, if you used it for wildlife:

• Pair with a Metabones FD-MFT Speedbooster to get a 210mm f2 lens
• Buy an older APS-C body (e.g. Fuji X-T2) and use with / without Metabones Speedbooster to get an MFT equivalent of 150mm f1.4 or 210mm f2
• Buy a Sony A7R or similar and crop when needed (i.e no Speedbooster)
• Sell the lens

More context:

I purchased a Mitakon Zhongyi Lens Turbo II to turn it into a 210mm f2 lens for times when I might need that, e.g. photographing swifts entering their roost after sunset. Unfortunately, it doesn't pair well with this lens and causes a fair bit of vignetting and does something that seems to kill sharpness. I have read that the Lens Turbo works MUCH better with other FD lenses, esp. slower aperture ones.

All the same, I love the subject separation you get from this lens, plus it's sharp. However it is a 40 year old design after all, and does not stay sharp enough with used with the MC-14 or MC-20 on a 20MP sensor, so I'm only considering using it with focal reducers.

Examples shot with this lens at f2.8:

Hanuman langur / Common gray langur

American goldfinch, breeding male

Happy Indian wild boar

Marsh crocodile / mugger