I was also 37-38 when I came across 531 and while I wasn't a rank novice I wouldn't have considered myself an advanced lifter. I had made a pact with some friends a year or two earlier to be "stronger at 40 than at 20". I sought out the advice of friends who had worked with 531 and advice from Jim himself.
Based on their advice and my own experience, I would grab the original 531 and forget about Beyond 531 for now. Then I'd run 531 with Boring But Big or a 5s Progression alongside. I'd add additional assistance exercises as directed and needed (KISS policy applies) and eat and sleep my way to some size gains.
Personally I'd do BBB for the volume, not just for "teh gainzz" but to get some time under the bar on the main lifts and get your technique sorted. Any stalls I've had in my progress that weren't due to me having to take time off were because of minor technique issues or a lack of work on supplemental lifts (hint: abs and lower back and then more abs and lower back). If you want to hit those goals, you're going to have to get bigger, stronger and know your lifts.
Of course, Boring But Big sometimes gets capital-B Boring. So you can always change things up for a cycle or two. Though I wouldn't do that until I'd run it solid for at least 3 months. The book gives you lots of options and I recommend you stick close to the text. Don't get too creative or think you can improve the program(s). Just do the damn thing and see where things go. I've tweaked a few things for myself recently, but only after a couple of years of running Jim's stuff pretty much verbatim and figuring out what worked for me. The mental gainzz from just going in and doing the f*ing program without trying to apply cheat codes or massage my ego with curls have been more important than the physical outcomes.