Sorry what do you mean by Acid test?
Was the system full of sludge when you first drained it? How long is it now taking to heat a full cylinder? How does it compare with the time it took before? I still think your best move would be to convert your system to fully pumped and get all the benefits that would give you.
What does it take to convert to fully pumped system?
How simple it is to convert is very much down to your personal skill level, an experienced engineer would think its fairly easy, you need to know your limits when it comes to DIY as its often cheaper in the long run to employ a professional. I questioned your understanding of your system from the beginning, you finished up having to replace the pump due to your lack of understanding, you had already told us your CH system worked so why did you feel the need to dismantle the pump? Many of us have spent years & years learning our trade and still we wouldn't claim to know absolutely everything but Im sure had I and many others spent less than an hour on site with your original "No Hot Water" problem we would have fixed it for less than it cost you for materials.