It's very unlikely to be the big ends, so long as you have been on top of decent oil/filters all the time.
I just collected my crank today and all it needed after 200,000 miles was a POLISH, no regrind necessary, the firm I use have effectively a open cheque from myself to do anything they consider needs doing machine wise, but shows they can last the mileage if looked after.
It sounds almost definitely like bore rock, that is chronic piston slap, where the wear is so bad that the pistons actual minutely try to rock in the bores.
This tends to affect the rear most pistons the worst as they run the hottest and wear the most, by this time the rings are usually a bit shagged, various clues to this.
The easy way to tell if it is the big ends is to park the car on concrete somewhere and rev the engine from eunder the bonnet with your foot on the floor by the front wheel, you can often detect a slight knock.
Your one doesn't sound like this at all to me.
My engine was going 100% perfect but it nearly needed 1mm oversize due to wear instead of 0.5mm, and had the same issues as you, although mine would go 100% silent just as you ease the clutch up pulling away.
tabetha