Core, yow; we weren't sweeping up raw memory, although it was sweet that our 2nd hand from the Logo Lab's PDP-11/45 had core, made booting from a crash easy unless the boot code had been scribbled on. I suppose you used some core because it was handy and DRAM was dear? If it was DRAM, I'd assume simply from the date and their partly being located in Worcester, it was Mostek, and I can imagine you itching to design a memory system with their addressed DRAMs. If you were familiar with the Intel 1103 from it being used (or so I was told) in the MIT-AI and Logo 11/45 display systems, and it being available, then that?
As I recall, LMI's CADRs used 74LS logic, but I could easily be wrong.
(Besides working for LMI in 1982-3 and playing with CADRs before then, in 1980 I started a student run computer center using the Logo Lab's then surplus 11/45; much of this I know from being told as opposed to direct knowledge, but I do have a weird memory for details.
And, hmmm, I guess I did a lot of salvage in the '80s; that student computer center eventually ended up with MIT-AI's KA10, and my EE friends marveled at the schematics, pre-standardized symbols and occasionally a gate's output would be hit hard to change its state.)