That injury means you had to get smart sooner than some of us.
There are photos somewhere on this forum of three 1400 lb. white oak rounds (4' dia x 20" long x 63 lb/ft3) sitting in my driveway, when I was about that age.
BTW... you're not getting into a
new big saw (eg. MS-661) for less than $1500, really more like $1700 after swapping up to a respectable bar and chains for cutting 40"+ logs. I don't know what used prices are now, but back when I was buying in 2013-14, the minimum you could get into an second-hand 064 or 066 with a new bar and chains was closer to $700. I suspect the equivalently-aged but bloated MS-660's today cost even more, despite having a really poor power/weight ratio, by comparison to its predecessors.
Either way, like you said... not worth it unless you're cutting that size on a regular basis.