How many miles are on it?
Does it do it parked or under a load?
Oil pressure still good?
Torque converter bolts tight?
A few things will start making a racket on higher mileage engines.
Timing chain smacking the front cover would be a good starting point.
What's a normal rebuild?
Budget rering & reseal or full on all the way?
Boring a block is generaly $15 - $20 a hole.
Cleaning tanking & inspection prolly $65
Then costs for inspecting the crank & rods, turning the crank (if needed), resizing the rods(if needed) & pressing in the pins.
Since it's at the machine shop anyway get it balanced. Mo $$$$
Chuck the heads in the scrap pile and get a set of vortecs.
Unless by some chance they don't need new valve guides and ya can get by with some lapping compound & a drill.
A generic kit with pistons can be had had for $200 or so.
Personaly for a stock engine I would opt for a crate engine.
What I paid in machine shop fees alone would have almost paid for a run of the mill crate 350 from a local rebuilder.
