Might not want HC parts either. the B ports on 6821s are TTL logic level which in some cases are controlling the 74154 decoders (Bally MPU).

Good part numbers

74HCT154
74LS154
74154

You want the N suffix (74HCT154N) to (dual in line through hole package) with 0.6" distance row to row (wide or unspecified)
The middle letters are family (hct = high speed cmos with TTL level inputs, typically a good choice for logic chips on old systems)

https://www.greatplainselectronics.com/proddetail.asp?prod=74HCT154

ebay.com link: itm

I have one of these things. It is nice to diagnose a bad chip, desolder it out and have that thing declare it really was bad. That is the main way I use it. It tests most 40XX, 45XX and 74XX chips including 74154. I have found a few odd balls it cannot do but for the most part reads them all back.

Some limitations. It can tell between CMOS and TTL outputs but cannot tell difference between HCT and HC. It also cannot tell between or no letters, LS, F and L. It does not test 74S assume because that family is a power hog. Some specialty types like 7437 will read back as 74LS00 because the pinout/gate logic matches. Also does test LM339 I noticed.

there are few ancient and obsolete 4xxx ones on the SB300 it can't do. 4562 shift register and at least one more I can't think of. I normally trust a new IC from auth dist. is going to be fine, but nice to check ones where I am forced to use old stock or salvages out of China.

Did get a bad $5 lm2679t5 out of the tube from digi key tho, so i guess it does happen.