A833 OD or 727 behind a 440. Suggestions and questions

A 10 inch clutch won’t even hold a 273, You will have to go with whatever flywheel and clutch that will match your BB belllhousing. Reseal the trans and replace the floating countershaft with a standard one. You will probably need to swap the bearing retainer to pilot into the bellhousing. And remember, don’t Power shift into O/D.