This!
The far eastern design shops will know their available parts and costs far better then you will and designing to take best advantage of a given part takes knowing what you have available for production.
Just tell your far eastern design house what you want to achieve, not how to get there (I hate customers who try to tell me how to design whatever it is they want, and I don't see a far eastern engineer feeling so very differently).
Note that writing a spec for a remote design house is something of a skill in itself, physical sizes, required standards compliance (and approvals, and what paperwork you will need), temperature range, MBTF (and method used to calculate it, and at what temperature), required ESD/Surge/Transient immunity levels, mounting holes, environmental classification, safety, tropicalisation ...., also your required lead times and penalties for failing to meet them, you need to spell it all out.
You should also specify what does not matter, if mounting holes can be re positioned, say so, it can sometimes save you money.
It is a very good idea to use a well recommended fixer in the area where your manufacturing is happening to deal with the differences in culture and to make sure you get what you ordered, costs a few quid but well worth it because they will know where the traps are (Also, budget to fly out a few times).
Regards, Dan.