The 1/2″ that GW shows when going from steel to graphite goes back a really long way, when the only graphite was super light. Now with more modern graphite shafts, that 1/2″ is no longer necessary just for swing weight purposes as it was in the past. No OEM that I’m aware of actually has a difference in length when going steel to graphite.
I would just stick with the standard 1/2″ longer than traditional you were fit into (37.5″ 7 iron for example). Then bend the lie 2* like you were fit for.
You can use this website to get a best guestimate for swing weight based on the standard weight details you get from the websites (be aware this can vary 2-4g at least) – https://www.valuegolf.com/golf-club-swingweight-calculator. Just put in the length of club, starting length of an uncut shaft, uncut shaft weight, head weight (plus ~3g for ferrule and epoxy), grip weight and see what it says.
A TS3 7 iron with PS+ shafts at 37.5″ playing length with REVL Element midsize grip is about a C8.4. Those grips are heavy at 59g, which drops the swing weight. A lighter grip will raises the swing weight, about 1 SW point for every 5g of weight differnce.
Thank you both for the advice and clarification. It looks like I will be adding some shaft weights to get around D2-D4.