Engine, Transmission & Header Install

I have a 1971 Scamp, with a 440, 727 Tran and Hooker Pro Comp fender well headers. I am converting it to a 833 and TTI under chassis headers. What is your thoughts on installing it from underneath instead of from the top? Do you think it would be possible to install the engine, headers and the tranny together from underneath? CD844DCA-430C-435A-92A6-8925192D223F.jpeg