I’m pretty sure there’s a template in Forever that is designed to let you work on improving other lifts besides the big 4. Can’t remember what it’s called off the top of my head… Jim used deficit deadlifts as the example. I think you still work the big 4, though. I just skimmed it.
What are your long term goals? If you plan on changing these frequently (even once a year is frequent in this case) its probably not a wise choice. If your only doing 1 pressing movement because your training 3 days per week that is not a good reason to skip the other, most of the 3 day routines are full body so you can bench one and OHP the other, and even repeat your favorite on the 3rd day. You can also do a 4 day split over 3 days per week so it takes a little longer to complete a cycle.
I’d pick Snatch Grip DLs over Romanian Deads, for a substitution. Romanian deads should be Assistance stuff (not Main work), like Stiff Legs DLs.
By the way, yes, you can get strong doing Front Squats / OHP / DL variation.
Not 100% sure what’s the rationale behind your choice tho, meaning, why are you doing it? What’s the goal?
If you only want variety, the substitutions would work best in your supplemental work - i.e. do regular back squats as main work, follow up with front squats for whatever supplemental work you program calls for (5x5 FSL, SSL, BBS, whatever)
If you want to do it, go ahead, the most used 5/3/1 rep schemes (like original 5/3/1, 5’s Pro and such) work well for other movements too - I remember an old article by Jim where he’s asked about it and he said he used them for power cleans and barbell rows too with good results.
For carryover, it depends.
I don’t think romanian deads have that big carryover in regular deads to the point they can be a substitution. Romanian deads usually help the lockout portion of the lift, much like straight leg deads help the initial push from the ground. They fit in the assistance stuff, single leg/core category.
You can do them and program them in 5/3/1 fashion but don’t expect them to actually improve your full deadlift unless you’re specifically weak in the second portion of the lift. And even them, I’d do full deads first and romanian deads after as supplemental (5x10 FSL, for example).
Regardless of what you do, if you’re training 3 times a week there’s plenty of great full body programs in Forever, you do each lift multiple times a week (properly scaled to be sustainable) and it lends itself better to substitutions
In short, all these substitutions lose their carryover benefits if you stop doing the main lift for an extended period, especially OHP/bench. Assistance lifts have some carryover to the main lifts, but you wouldn’t call tricep extensions a bench variation even though they work muscles that carryover to that lift.