386 Motherboards vs. Acceleratr Boards

[Benyukhis]

Need a lot of advice on upgrading 286 to 386 (ideally one would sell one
and buy the other... but it is impossible to sell the used machine
for as much as you have already invested so ....)   I am looking
for an information on how to upgrade an AT type machine to a 386 i.e
what are the available products, known limitations, etc.
For information: I have a PC's Limited 286 AT 6/8Mhz switchable with
Phoenix BIOS, 40Mb ST-251, EGA, and 3MB (120 or 100 ns RAM)
1024 on the mother board and 2Mb on the Everex Ram board (3000 I beleive)

I need all of the information I can gather (prices too if known)
Will summarize the results to the net.

Thanks much,

Edward Benyukhis