I don't want to do this job, but if its a fixture plate, you may want to consider mic 6 aluminum cast plate. it will be flat on both sides not requiring machining. and then I would add heli coils to all the m6 threads to ensure they don't pull out with repeated use. yes it will make it more expensive but its the right way to do it.
Thanks for the heads up and I've awarded the job.
Thanks to all who put a bid in.