Luis;

I agree with other posters...buy and install a quality 180 Deg by-pass type T-Stat...they are not the place to save...and T-stat must be 180 for D-Jet to run correctly...if running Hot, assure fill level first...if OK, flush Rad and Block (use Block Drain left of Oil Filter!)

AC Rad may be in series with Rad airflow, but I doubt it influences the airflow that much to alone be the cause of running hot...but the little difference it makes will contribute when other factors reduce cooling...at highway speeds, it makes no nevermind! You can verify this by turning OFF AC so it doesn't preheat air going through Rad...nah, your cooling issue lies elsewhere!

My view on Alu radiators with our iron blocks: They look nice and shiny sure, so they sell a lot of them, but are the anode in the galvanic couple between iron block and Rad...so THEY will corrode (from the inside)...and being THIN Alu, they are only a short term solution which will NEVER last as long as the original Brass Rad and Heater Cores (where the MASSIVE iron block was the anode and could loose lots of ions without issue)...but the guys selling the shiny Alu Rads will never tell you this (because they like to sell them)...ask at a Rad shop how many Alu Rads get replaced.

My recommendation: Flush Cooling Sys well, and when necessary, repair your brass Rad or when fins are really externally corroded and gone, have it recored with new brass/copper core, which will last another 50 years!

Cheers