Engine/Gearbox Removal

Hello list,
 
My 69 Sprite tends to slip out of fourth gear unless I keep my hand on the gear 
stick.
 
It's annoying to say the least and I know I will have to deal with it.
My question is, how feasible is it for one person, unassisted,  to remove and 
replace the engine and gearbox? 
 
Thanks in advance.
Rob.