matty89, INA are the aftermarket lifters.
Many owners and mechanics would not use INA lifters because they tend to fail soon.
Most owners would trust good Porsche OEM lifters that are 20+ years old.
You might want to place a WTB-(want to buy)
"good used lifters for 944"add on the Pelican forum for used parts classified:
Porsche 924/944/968 Used Parts For Sale & Wanted - Pelican Parts Technical BBS
I did just see a set of 8 on eBay also.
GL
John