Do it in the twin....
For a few reasons.
1. When you are looking for your job, you are already 50 hours closer to the twin requirements.
2. Your instrument rating will be MUCH easier as you are already familiar with the concept and speeds of a twin.
3. When you sit your CPL test, it will feel easier as you are used to more complex faster aircraft (like getting back into a warrior after an arrow)
As for the costs, think of what it might save you down the track:
1. Faster IF rating
2. Don't have to private hire a twin to make minimums for company requirements
3. If you are instructing, you have the minimums for Multi Training should you choose to.
I could not recommend it enough, and wish I had the $$ when I was doing my training as you seem to have.
Good Luck
CS