Respec in A4 NM from firelock to ES

My main issues are that I'm playing offline and time is limited. I've read I should find a 4 socket weapon before respec. A 4 socket poleaxe just dropped and I could make Insight out of it, but the base damage on this thing is 18-39.

Will that shoot way up once I make Insight?

What weapon or weapon base should I be looking for if not this one?

Any advice appreciated. I'm a D2 OG but I never messed around with runewords back then. Thx