https://parishkneelers.co.uk/ - resource and grants advice
Spoke to Di at Parish Kneelers who shared that the company was st one time the largest ecclesiastical wool supplier in the UK.
She recommended that a 12 count canvas with wool tapestry thread in a tent stitch would suit the project for speed, feel and resilience.
She referred me to the portrait kits on their website by Emily Peacock as reference for this finish.