THISabsolutely begin with a later block that either has OE roller lifters or can accept them.
JMO, 87-95 350 heads are lousy.
96-02 rpo L31 (350) engines have it all: roller lifters, one-piece rear main seal, thin metric piston rings, and best production heads yet (iron Vortec). Some of these blocks' mechanical fuel pump pads are Not completed. But with EFI, you won't be using a mech FP. L31 are ubiquitous but only in 96-02 Chev/GMC mid & light trucks when eighth character in VIN is "R". L31 also found in many marine and industrial applications. All OE 79 brackets & accessories should bolt up. FWIW, all 87-up crankshafts are for the newer one-piece rms and they all have a smaller bolt circle than earlier motors; requiring later flexplate. Flexplates are cheap to buy.