A part 147 cannot issue a OJT certificate, The OJT is a function of a part 145.
A Part 147 can issue a Practical Training Certificate which is appox 10 days duration as you say. This along with your theroy certificate will be sufficent for the type to added providing you already have a type in that sub-group.
For your first type rating you will require
A Theory Cert
A Practical Cert
(Both from a 147)
+ your OJT (from a 145)
A lot of people are confusing Practical Training & OJT, they are two seperate things.
Hope that make sense