I'd like to bring my old 1e master transmuter character back in 2e form. How might I best accomplish that?
I recognize that he won't be quite as powerful, due to all the tight math rebalancing I keep hearingabout, but if we can at least get the flavor of a "mad wizard that turns into savage beasts and devours his enemies with ease" then I think I'd be quite happy regardless.
Any advice you could offer would be most appreciated.
Well, it's a complicated question to answer.
From a purely flavor point of view, you can still build a Transmuter and use the various Battle Forms to enter battle. The first form you'll have access to is Ooze Form, which is a spell level 3 (so level 5 character). Before that, you won't be able to play it as intended.
I encourage you to choose a Specialist Spell Blender, so you'll have the maximum number of highest level spell slots as Battle Forms are only valid on your highest spell slots, just a level under that and you'll feel useless.
From an efficiency point of view, it's not incredible. It's not utterly bad but the martials next to you will feel more powerful without having to use limited resources for that. You'll be an honorable damage dealer, but not the best damage dealer. Also, you'll have 5 or 6 Battle Forms a day and then you'll be back to "normal Wizard". It's also important to know that once in a Battle Form, you can no more cast spells. So if being able to both cast and devour enemies is important, it's no more possible.
The last issue is a rule one. There are a lot of discussions on damaging runes and if they should apply to Battle Forms. They should from a balance point of view, as without them you'll be another step behind the martials. But many GMs won't allow them so you should really speak with yours to decide that.
I'm not sure it's the most thrilling answer ever, but you hit one of these builds that are no more working easily in PF2. Roughly, PF2 separates casters from martials and it's very hard to be a competitive martial with a caster or a competitive caster with a martial.
If I can give you a last piece of advice: Consider PF2 to have nothing in common with PF1. They are extremely different games and just don't work the same. It's the best state of mind you can have. The faster you get away from PF1 reflexes and the better you will handle the transition. Bringing expectations from PF1 to PF2 can lead to a lot of frustration.
And expecting to play a PF2 Wizard the same way than a PF1 Wizard is one of these expectations that led to a lot of frustrations in the early days of PF2. If we sum up all the "Wizard is weak" threads there are literally thousands of posts. If one of my players come to me with your question, my first answer would be: "Are you really sure you want to play a Wizard in PF2 like you used to play in PF1?". And I'll certainly ask the question multiple times until I'm really sure they love the flavor of the class but not its power level.