We are building a lot of Holden V8's these days. Everything from street cruisers to full race boat engines. I recently did a Ski boat engine -not a hottie but a good quality ,reliable build with well matched parts, cost about $4500. We are currently doing a Race Boat engine, 253, cost with all systems-i.e. ignition, carb, exhaust, cooling, will go well over $20K. Keep in mind a good ignition "sysyem" will set you back $1350. The labour for this build is about $8k. This includes a lot of flowbench time and head work- alighn honing the main tunnel, the conrods have about 9 hrs labour put into them A9l, radius milled top and bottom, beam polished, new bolts , resized, Shot peaned,pin bore mods.Several mock up builds required to get deck heights , valve clearences, rod clearancing etc. Crankshaft needs a lot of prep work before grinding and balancing to ensure that the assembly can be internally balanced without heavy metal.
What i'm getting at is that if you are rebuilding a 30+ year old engine and wanting to improve performance AND have durability ,there are many area's that need attention.
One not one your bores only needing a hone. Bores can LOOK ok but run a bore gauge through and you will see some startling deviations in size, shape , roundness, Taper , wear.
As for your build,I would think you would need to spend $3.5-4K on labour/ Machining plus parts.
Otherwise grab a cheap 355 kit, cheap alloy heads, cheap manifold, decent cam, basic L34 heads and screw it all togeter for probably about $7K with machining.What could possibly go wrong!
Hope this helps.
Cheers