Gain muscle mass while staying lean? (Calories and macros question)

Hi Everyone, I’m new to the forum and I also don’t know much about using forums, so please forgive me is this type of post is already being discussed here or something.

I’ve lost about 45 lb this year (I was like 193 in August last year). So, finally the gut is almost totally gone. Now I’d like to do a “lean bulk,” which I understand to mean building lean muscle mass, but without packing on the gut again. The common wisdom seems to be you have to put some fluff back on to gain muscle and then shred it off, but that idea is less than thrilling to me since it did take me my whole life to finally figure out how to lose the gut.

I do like to follow Jeff Cavaliere’s AthleanX YouTube channel, and he seems to believe that contrary to popular opinion, a lean bulk is not only possible, but preferable. That was very encouraging to me, but while his nutrition advice is very good, it’s a bit vague and very generalized —in other words, it doesn’t help me calculate things, and I’m very calorie/macro oriented. Tracking nutrition just works incredibly well for my personal fitness style.

Looking into some things myself, I came across this MFP blog article:
https://blog.myfitnesspal.com/the-basics-of-body-recomposition-macronutrient-calculations-to-lose-fat-and-gain-muscle/

The article seems great, and it also raises a lot of questions for me as I work to figure all this out. I’m wondering if I can find some answers here so I can hopefully get going on a new plan. I’m 45, I’m 5’ 10’ And I’m 147 lb. — and according to body fat calculators, and according to my neck and waist measurements, my body fat is 17% or so, and lean body mass is like 121.3 lbs.

I’ve done some calorie and macro calculations based on the info in the article at the link above, and based on a part 1 of that article’s series —and it looks like these here are my numbers according to the article’s calculation system:

Maintenance calories —2520
————————-

Training days calories —2898
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P 220.5g (882 cal)
C 220.5g (882 cal)
F 126g (1134 cal)


Rest days calories — 2268
————————-
P 220.5g (882 cal)
C 51.45 (205.8)
F 131.1333 (1180.2)

I’m psyched to dive in and get going with this as the basis for my nutrition plan. My one concern, I guess, is that up to now my caloric intake has been much lower than this —especially the fats. I do think the above probably makes sense, since we’re talking about the nutritive needs for building muscle, but, do my calculations in fact seem right?

I’m just surprised at the caloric amounts, and especially the amounts of fat... I know fat gets an underverdly bad rap, but the fat intake this article’s author states for himself is a fair amount lower than what I’ve calculated for myself — I think that could make sense too, because of height and weight differences between us, but, whoa!! While I want to build muscle, I do want to maintain the newly acquired lean physique I’ve finally achieved this year after 20+ years of trying and failing. Curious as to people’s thoughts. Thank you for reading!