Yes, on mild"ish" turbo setups using 68mm or smaller turbine wheel setups, I've always gone faster shifting at 3k rpm. Even with the 73mm turbine on the Junker with the big HT80 89mm atmosphere, I still only shift at 3500 rpm or so. I'd say the sweet spot on that setup is 2700 to 3600 RPM.
Pull some timing would help.
I dont think your asking too much. Purple power works good in the coolant system for cleaning the mess
Don't lug it down so low in the rpm range.
ARP recommends 150 ft lbs with those studs (625's), most go a touch over the recommended torque spec, so I'd say you're a little light on the stud torque at 145 ft lbs. With cheaper ARP 2000 studs, I was never able to keep the headgasket alive with orings until I torqued them to 155 ft lbs cold, warm retorque , warm retorque after a couple hard runs, warm retorque again untill they quite moving during the retorques.