CR = compression ratio, this will be around 8 to 1 on a std cossie, if using a different than cossie head could be even lower depending on chamber volume in the head.
No good unless for turbo applications, as just too low, assuming it's for a non turbo car then use 2.8 V6 cologne pistons in +90" form for 2086 CC!!
Last set I bought were £38 for 4 pistons.
tabetha