1960 GMC 261 cu/in to adapt to Turbo 350?

[Legend56BC]

My daughter brought home a 1960 GMC with a 261 cu/in(6 cyl) and a 3 spd standard and she wants to convert it over to a Turbo 350.I know or think I would need a trans adaptor of some sort or is there a kit of some sort out there?I remember many years ago something abought using a cast itron powerglide adaptor but thats about all I can recall.I have a 327 here and she could put that in no problem but she likes those big 261's and wants to keep it as stock looking as possible..