Copying factory tunes and import to aftermark ECU

Is it possible to get factory tunes from factory ECU and copy them into an aftermarket ECU. Download stock rom maps, get the figures from fuel and ignition tables then copy the values into an aftermarkt base maps. This is for a stock motor that is swabbed into different chasis. I think it can save dyno time and costs.

Technically you could go some way towards taking factory map data however the biggest issue is that most factory ECUs use a MAF sensor for load measurement while most aftermarket ECUs use a speed density system. This means there is no easy way to correlate the load points on the tables. The other issue is that the way a factory ECU deals with fuel delivery is usually different to an aftermarket ECU and hence it's likely there isn't actually a fuel or VE table to copy across -Often a factory ECU will just utilise a target AFR table.