PC Transporter Rev. E (“Little Blue Limited”) – RAM Expandability

Hi everyone. I’ve got a chance to pick up an Applied Engineering PC Transporter “Little Blue Limited”, but I’m trying to sort out a few technical details before pulling the trigger. This unit has six TMS 44C256 DRAMs installed — they’re the only socketed RAM chips on the board, which makes me wonder what AE actually wired up on this early revision. I’m trying to confirm whether this LBL Rev. E can really be upgraded to the full 768 KB configuration, and if so, what specific DRAMs are required for the expansion (density, speed, and whether AE expected 256K×4 or 1M×4 parts on the unpopulated positions). Any info from someone who has worked on one of these pre‑production boards — or has documentation from AE’s internal upgrade notes — would be hugely appreciated. Thanks in advance to anyone who can shed some light on this oddball revision.