Hey lambertius,
I would talk to Mark D'Sylva in Toronto, Canada! He was willing to work with me to tune my stroker with Dbilas ITB's on the stock E30 ECU. Not sure what he'll say about the E36 and reflashing but it's worth a shot.
http://www3.sympatico.ca/mdsylva/products.htmI would also talk to a new member apexspeedtech.com here on the forum and a master at tuning. He's in California, USA
Here is Neel's link
http://apexspeedtech.comI've done all the above you mentioned
Going on info from an old timer in the mechanic field, I advanced the intake cam timing on a stock M42 motor and stock cams 3-5 degrees with a Jim C chip and I thought that it wasn't as good as the stock cam setting. So my suggestion would be to go with a stock manufacturer setting at first and then play around from there. When I built the stroker I had a friend design a custom cam profile that would give lots of torque across the rev range. The torque band was flat which is great for the street. The E30M3 S14 Evo2 came with a special exhaust cam gear to scavenge for more torque. When you changed cams it just wasn't worth it anymore so it may only have been good for stock cam purposes. You'd really have to play around with cam gears and cams to find the optimal tuning for your application.
I've also done a lot of cam work with the E30M3 S14 with a 2.3L and 2.5L. I've had stock and Schrick's and regrinds that mimic Dbilas or BMP cams(which were Dbilas cams). Schrick cams are like having an on/off switch, more raw; the power comes on hard. One sec it's not there and then you just take off. LOL
I now have a shim under bucket set up on my 2.5L S14 with 304*/296* regrind Dbilas cam set up. The motor makes 330+HP at the crank. These cams are so much more refined and progressive than the Schrick's. The power is so much more linear and it's very deceiving! I've heard Cat Cam could be another option but I have no experience with their cams. If I were to do cams for a M42 motor I would go Dbilas. They have great customer service as well!
That S14 motor also has a stand alone ViPec ECU on it. So much more control with a stand alone. My M42 stroker had MSII running Alpha N and MAP making 212HP at the crank with mild street cams. I would find out what your local tuner likes to use and go with that option. It will save you time, which is money, so they don't have to learn a new system. Remote tuning is also an option and requires buying a few toys to log your runs.
So you have lots of options to choose from and they're all great ones! bmwman91 is setting up a custom stand alone and then there is Neel who is a new member but known to some of us in the stand alone and BMW world as well for his masterful tuning expertise!
Here is the link that bmwman91 is working on with the stand alone project.
http://www.m42club.com/forum/index.php?topic=20113.0 Hope this helps!
Cheers mate,
~Ralph