The biggest piece of advice I can give you is to have it THOROUGHLY checked out by a certified Mercedes tech who is familiar with older models and all their quirks. The money you spend will be well worth it. The seat covers for the interior can be replaced in MB tex for $300. I do not know how much other interior parts cost. Also, if one of the techs is reading this, I have a couple questions about my 1975 450 SL, I wanted to know if you can remove the catalytic converter and retrofit one further down the line in the exhaust to where it is on the later years? This would eliminate the excess heat generated by it being under the hood but still have the car pass emissions tests. Also, my battery is in my trunk and I thought the battery was not move to the trunk until 1978? Thanks for any advice you have.