I don't know about other manufacturers, only really owned Hondas. I do have a TDR but that's because they are a little crazy. Has small carbs though.
I think with a decent exhaust and carb, you will release enough power and then the porting can be done later. Who else could do it; I don't know. The cylinders are really cheap and available.
I will have some free 250 carbs available but no time to hunt them out - just been told I'm needed in Singapore next week and still need to go to the UK. My free time after I've typed this will be measured in minutes. If you're still looking when I come back, I will find them for you. Also have jets coming out of my arse if Andy's suggestion doesn't work - sure it will though
From what I know, the 250 master should be a straight fit. Think the 250 is 14mm which will be a couple more than the 150
Red Baron in Bangkok sell some really cheap original brembo stuff and Bangkok is full of fake stuff 
It would only cost a few baht to find out but can't imagine why it wouldn't work with the original callipers etc.
Bangkok is the place to find parts. I guess you have looked on mocyc.com - shows you what bikes are over here. Some cheap bikes and parts on there.
If you insist on carrying the misses, I believe YSS make shocks for the 150 over here. Don't know what they are like but very cheap and always good to support Thailand.
You don't need a shop to do the rebuild; give it a bash. Bet you live in a condo though and can't fit the bike in the elevator.
Peppermint is in walking street Pattaya. It's somebody's favourite bar. It's also above another bar where you can find lots of 'ladies' called Billy if you know what I mean. Bet they are good on bikes though.
What are you doing over here?
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mc18 F3, mc21 300, mc21ish sp, mc21/28ish.
cbr929, RC30, tdr250, rvf400, wave, gyro, joker.