Hi Jordan – sounds like you are mainly interested in solid-state replacements for 01A tubes as used in the AK 20C and AK30, and for WD11 tubes as used in the Radiolas. A popular replacement for the 01A is a circuit using a small light bulb and a photoresistor with an FET, with a detailed discussion here:
One point noted in the ARF thread is that you might expect to have to do some tweaking of each stage in a TRF to get it to work properly with all SS replacements.
For WD11 replacements in my Radiolas, I have recently fabricated substitutes using miniature 5676 tubes inside cut-off test tubes attached to custom bases, and hopefully will publish the construction details in a future issue of the CVRS Newsletter. I haven’t found an FET circuit to substitute for the WD11 so have taken it as a challenge to come up with one for the Newsletter at the same time.
In general, the SS replacements I’ve tried work quite well. The solid-state 1L6s in my TransOceanics give better performance than the original tubes.
You also mention trying ‘Radios on a Chip’. Not sure how you will get at the input to the detector inside the IC package, but the venerable MK484 chip (now TA7642) is available on eBay at 10 for a US dollar (with free shipping!).