Considering First Cycle

I have a situation and question similar to Malfeasance.

My background;
Pushing 54 yrs, been training non stop since I was 13.
Lifetime natural as far as the real deal(for a bunch of reasons that are irrelevant to this post) but Ive done various over the counter prohormone cycles on and off for maybe 15 yrs starting with Biotest original MAG-10 which I believe was test 1.
The thing is I’ve only done 6-8 week cycles and only during the last 6-8 weeks of my annual cutting cycle in spring to get ready for summer. So I never really got to go all out and try a mass gain cycle. I basically retained strength for my cutting phase each yr and try to gain strength and size in the off season naturally.

I am a genetically “skinny/fat” body type. Difficult gaining strength and get soft easy but not obese.
Small joints ,narrow clavicles, narrow hips and high short muscle attachments.
To keep it brief the macros of my standard diet are basically 200-250p, 200-250c, and 50f per day. I try and center carbs before and after workout.

I would say I have a sluggish metabolism because in final weeks of a cut I’m down to 15-1600 cal a day and many times less and its usually keto with occasional carb up and 45-60mins a day of cardio 5-6 days a week.
I also have poor digestion and cannot take in a lot of fat or protein due to poor appetite and also because I’m still burping up meals hours later. So I basically try to compensate with very easily digestible food(Plazma, MAG-10, whey drinks) to get the nutrition in.

I’m 6’0 tall and in my pic weigh just under 200. I’m guessing around 7% body fat.
My goal is to put on a permanent 20lbs. I’d probably be happy with 10-15. I’ve been chasing that 220lb (but fairly lean) mark my whole life and can’t get it unless I get fat.I just keep gaining and losing same 20-30lbs.
I do have some nagging injuries/surgery but still can do all the heavy basic compound movements. Even more so on a prohormone cycle because all the pain temporarily disappears.

At my age is gaining this much lbm even possible? Is it even possible in one long cycle or several?And if so what do you recommend?
I also do blood work before an after cycles and sometimes during the year to see how certain new supplements are affecting me, ie test boosters etc
Sorry for long post just wanted to get it all in. Thanks

Sorry this question was supposed to be posted in Sahdow Pro’s thread