Will lt1 heads work on a 72 Malibu 350 block?

 

it takes some modification...And I don't know what exactly...But it can be done.

a machinist would know what has to be done

 

like said, a straight bolt on, its not gonna work. LT1 heads are reverse flow cooling.

it can be done but is it worth it?

 

Vortec heads have the same porting as the lt1 heads, have not verified but source is reliable. Intake to head match is the same with vortec as with the lt1, your intake for 1972 is not a perfect fit but can be made to work.
For what you will spend on purchasing and modifying the lt1 head to suit your engine the vortec will do the same for less. If you want aluminum look at Trick Flow or the 113 L98 Corvette heads.

 

Good advice here. The Vortec head actually outflows the aluminum LT1 head on the intake side. The exhaust side needs some work though. A weekend could fix that. Along with the head conversion, you will have to re-drill the intake bolt holes.