We don't use times here since people are in various time zones. We use hours since shot. I'm still not clear on how many hours after insulin you got the 62 and 52. Your first post said 'gave him his morning shot' then said 'around 5pm he is at 62'. You last post said 'his shot time was at 12:00'. So, if it was a 'morning' shot that would mean 12am which would mean there would have been another shot time at 12pm before the 5pm test.

If the shot was at 12pm, then 5pm would have been +5 (or 5 hours after insulin). Is that what it was?
With ProZinc, the nadir (lowest point in cycle) can occur anywhere from +4 to +8. When Mia was on ProZinc, it was pretty consistently at +6. It is helpful to know where the low number occurs within the cycle so that you have a feel for whether the cat is likely to continue dropping or if they are most likely about to take an upturn. Either way, 52 is definitely too low on an AlphaTrak.
When you say he is on the lowest dose of insulin, what dose is that? The lowest dose would be 1 drop. Are you using U40 syringes, and if so do they have 1/2 unit markings? Or are you using U100 syringes and the conversion chart (which always for smaller dosing increments)? Whenever possible, it is usually best to give a dose that can be given pretty consistently rather than having a dose that is too high and causes the cat to go too low to the point that you cannot safely give the next shot. For example, if the cat is getting 1/2 unit dose and they go too low on it causing you to have to skip a dose, it is usually best to then drop the dose to 1/4 unit at the next shot time. Consistency goes a long way in helping keep things 'smooth'.
The good news is that it sounds like Geppy is responding well to the insulin! And, you are testing, so you caught the low number and knew to feed him to keep him safe. Good job.

If you would like assistance with fine tuning the dosing, you may want to post on the ProZinc forum so the members with the most experience with that specific insulin will see the post and can offer advice:
http://www.felinediabetes.com/FDMB/forums/prozinc-pzi.24/