adjustable coilover dimensions

Does any one have any recomendations for setting the tube length and threaded tube height on I believe a capri strut (bolt on arms) to suit a Mk1 escort race car. And any Knowledge on what brand insert can be used to help lower the car to 100mm at the lowest point.
I am building another set of adjustables with enough travel to suit racing as the current set isn't low enough and it rides on the bump stops. Im guessing I need about 50mmm of travel and therefore need to shorten the strut tube by 50mm also and the threaded section should be about 10-20mm from the top of the tube.
I hope to use Bilsteins but if something else suits ill consider it.
Thanks
Justin p
I am building another set of adjustables with enough travel to suit racing as the current set isn't low enough and it rides on the bump stops. Im guessing I need about 50mmm of travel and therefore need to shorten the strut tube by 50mm also and the threaded section should be about 10-20mm from the top of the tube.
I hope to use Bilsteins but if something else suits ill consider it.
Thanks
Justin p