today I ramped up front of car ad tried again with my new tool, which is the top of a plastic water bottle with lots of tape around the cap area shoved into the rad' opening. I ran engine to warm and kept pumping the top pipe and some more bubbles came up. Also I put original temp sender on and the temp shows about 3/5.
Overall I am comfortable but ordered a new voltage stabiliser to be sure the full loop is tested. I did find the laser heat pointer a great help and re-assurance.
Last, the engine block fluid is still is a bit brown but I recently spoke to a bloke who is a heating specialist and he said avoid the acid flushes and just keep changing the water/coolant on a regular basis. He gave some good reasons and mainly it was based on it being too aggressive and an excuse for poor maint'.
Top tips from the forum have been lifting front end, pumping top pipe, checking sender but an independent heat tool was a great help. what a great forum and community we have here.