Heres the information I could find, I'm on 12.1(11)T which fromt he documentation I found on the 2600 series it is supported. Not sure about memory usage thought.
Cisco Internetwork Operating System Software
IOS (tm) C2600 Software (C2600-BINS-M), Version 12.2(11)T, RELEASE SOFTWARE (fc1)
TAC Support:
Copyright (c) 1986-2002 by cisco Systems, Inc.
Compiled Thu 01-Aug-02 13:10 by ccai
Image text-base: 0x8000809C, data-base: 0x817475B8
ROM: System Bootstrap, Version 12.2(7r) [cmong 7r], RELEASE SOFTWARE (fc1)
Lowell uptime is 17 hours, 8 minutes
System returned to ROM by power-on
System image file is "flash:c2600-bins-mz.122-11.T.bin"
cisco 2651XM (MPC860P) processor (revision 0x100) with 58368K/7168K bytes of memory.
Processor board ID JAD064004DB (133421137)
M860 processor: part number 5, mask 2
Bridging software.
X.25 software, Version 3.0.0.
2 FastEthernet/IEEE 802.3 interface(s)
8 ATM network interface(s)
32K bytes of non-volatile configuration memory.
16384K bytes of processor board System flash (Read/Write)