Hey.. i have done the mod by myself but didn’t use an 1mm shim.. Had some copper sheet laying around but only 0.1mm, so i did cut 3 pieces, used some standart thermal paste (cooler master v1) in between.. package was around 0.5-0.6 mm.. till now nothing is moving max temp at 80 degree celsius.. so your 1mm shim schould got even more pessure..
and of course some thermal pads on the back of the heatshield (completly covered, ordered some cheap chinese ones), schould help thermal spreading on backplate..
greetings from germany
and a big thanks to Chris G for his awesome work