Hey there,
In a word, no. I had a look at the software downloads for pix and sorted them by release:-
PIX OS version 6.2(2) software. Requires a minimum of 8 MB Flash and 16 MB RAM 6.2.2.ED 28-JUN-2002 1658880
pix624.bin
PIX OS version 6.2(4) software. Requires a minimum of 8 MB Flash and 16 MB RAM. 6.2.4.GD 22-JUL-2004 1677312
pix635.bin
PIX OS version 6.3(5) software. Requires a minimum of 8 MB Flash and 16 MB RAM. 6.3.5.GD 07-SEP-2005 2101248
pix701.bin
PIX OS version 7.0(1) software. Requires a minimum of 16 MB Flash and 64 MB RAM. IMPORTANT - Read the Guide for Cisco PIX 6.2 and 6.3 Users Upgrading to Cisco PIX Software Version 7.0 and Release Note prior to downloading this release. 7.0.1.ED 02-APR-2005 5124096
pix702.bin
PIX OS version 7.0(2) software. Requires a minimum of 16 MB Flash and 64 MB RAM. IMPORTANT- Read the Guide for Cisco PIX 6.2 and 6.3 Users Upgrading to Cisco PIX Software Version 7.0 and Release Note prior to downloading this release. 7.0.2.ED 22-JUL-2005 5124096
Then there is more 7.x releases.
HTH
LH