Irene
I am not sure how many graves would have been moved when the Columba Club was built - perhaps some one at St Conval's would know. There are still a few (very few) readable stones in the old church grounds, next to the Columba Club car park - but the grounds are not well maintained.
When they moved the gravestones from the Old White Wash Kirk (now the Sports Centre car park), they were supposed to be interred in Neilston cemetery, but to be honest, I have struggled to find any of those stones in Neilston.
If you wish a note of the readable stones in the Old St Johns, I can go up and note the names and dates for you.
Regards
Z