Flexplate problems

Hi Guys
Need a bit of help?

I am currently swapping SBC engines over in my 47 sedan, the 47 was fitted with a "built 350 chevy engine" which is going to be fitted in the 37 phantom.So I decide to buy a 305 chevy from a supplier in the UK.

I have come to swap the flexplate over ,but the hole in the centre for the crank is to big,the flexplate has 168 teeth which fits the starter motor,and the torque convertor.
Am I right in thinking I will need a 153 tooth flexplate along with another starter motor and torque convertor,if so this quick and cheap changeover is becoming expensive.?
The end of the crank on the 305 is round with a centre boss of about 2 1/4" and looks to be a 1 piece seal.
Does anyone know if it is possible to get a flexplate to suit the crank of the 305 and the torque convertor of the 350.

?
Thanks Guys

The one piece seal cranks also have a smaller bolt circle so you can't mix up the flywheels---also, the one piece seal cranks are externally balanced so the flexplate will have a balance weight on it---it will fit the tq converter and most blocks hve starter bolt holes for mounting what ever starter is needed

Jerry they still make a 168 tooth flywheel that will fit that right, the differance is just the center hole and external balance weight???
In other words he does not have to go with the 154 tooth flywheel, right.
Kurt

Guys
I had a busy day yesterday searching websites and have found this TCI Auto: GM 168-Tooth External Balance Flexplate which looks to solve the problem, I will try and speak to some suppliers over here today if any are open as its nother Holiday weekend. I let you know how I get on.Thanks
Dave

that flex plate will solve the problem of the flywheel but the block/starter needs conpatable mounting holes---they all aren't the same---also block may or maynot have fuel pump mount----and if it has the mount , the drive hole may not have been machined!!

Well just a quick update.

Eventually got the flex plate ,after it being lost at customs for 10 days,got everything fitted last weekend ,even fired up 1st time,which is a result for me,but I had a squeak coming from the transmission end, had a good look around but couldn`t find anything, but after 3 days of putting everything back together I needed a break so shut the garage door and walked away for a couple of days,had a chat with a few folks and decide that the best course of action was to jack the car up and crawl underneath and have a good look using a torch whilst the engine is running,on firing up he engine i could still hear the squeak, if I put it in drive it got worse,so I am thinking I am going to have to take this engine out again,but once i got underneath i could see that the flexplate was touching the end of the starter motor,as it was a mini starter I could make up a shim and get some clearence which i did ,with my fingers crossed I fired up the engine and no squeak, hooray,lowered the car back down on the ground and went for a drive,and I can now report that all is well and the engine runs great.Just got the drive way to clean as a hose went on the transmission and I have ATF all over the drive. Good job the wife "loves me".
Thanks for your input guys, a happy ending so off to the NSRA fun run at Billing on Wednesday,about 200 miles.
Dave