Front suspension to coilover query 45mm-51mm

[Dogmot]

Basically I have a 1988 316 and it's got the 41mm or 45mm (can't remember the exact size) front suspension from factory. The car is fitted with a 1996 325 engine and e36 rack, going to turbo the engine etc. Am I best purchasing some 51mm front e30 325 struts to chop up and weld to the new 51mm coilovers?, is 51mm really necessary as an upgrade or am I perfectly fine buying coilovers to suite my 45mm struts? Thanks