Great stuff right there. Just for the fun of it, I tried to convert the prices for the 3 liter motor to today's values in USD. I used this site for the method:
historical currency exchange rates between German Marks and US dollars, 1913-present: tables and sources, also inflation calculator links.
marcuse.faculty.history.ucsb.edu
As always, things are not as easy as one would think. There are many ways to calculate the inflation rate over the years (see the above site if you really want to go full nerdy). The "low end" 230PS motor was 4995 DM which converts to $1880 in 1973.
That, in turn, would be equivalent to somewhere between $12,400 and $14,400 depending on which inflation parameters you use in 2022 (the last year that converter works for).
At the other end of the scale, the 360PS race motor was 30,000 DM or 11,320 USD in 1973.
That would convert to between $74,500 and $86,000 in 2022
No small change either way!