@kythyn, great price on the T-IV’s! They’re worth about twice what you paid for them. I have a pair of T-IVa’s (I sold my IV’s a year ago, but not for $1k ;-), and if at all possible, yes, bi-amp them. But to do so well will cost you more than $2,000.
First, you’ll need an electronic x/o to provide the 1st-order high-pass and 3rd-order low-pass filtering. The First Watt B4 and Marchand’s are popular with Tympani owners, but the old Dahlquist DQ-LP1 provides that exact filtering, and can be picked up for around $300 (sorry, I sold mine just a couple of weeks ago).
As you have discovered, that great T-IV ribbon tweeter really tells you what the high end of an amp sounds like, so you may want to consider tubes. But the speaker is a 4 ohm load, which tubes don’t like. That is less true of the Music Reference RM-200 Mk.2, however, a great amp for the T-IV (if bi-amping).
For the bass panels, there is no such thing as too much power. Tympani aficionado Satie over at The Planar Speaker Asylum (a great source for all things Maggie) uses a Crown Macro Reference (2000w/ch @ 4 ohms).
If the above is out of reach, look into finding a used Sanders Magtech amp, and forget about bi-amping.