Mate you are deffinatly not alone, at least take that to hart,
dont hate your R because it has let you down, accept it, rebuild it and enjoy it, thats why you bought it.
Common sense would say if you have the engine out which is gunna cost you $1200 - $2500 (it is a certifiable bitch!),
you may as well rebuild the top end also, its pretty old now if its still original internals. You are going to have to accept that its gunna be between $5k and $10K depending on what you do, $5k you should get your bearing, pistons (hone and bore) and labour, thats about it. For a nice build you wont have to worry (too much) about your looking at $8k-10K .
I my self have just been through the same thing. Trust Nick and Pro Engines they know what they are talking about, if you want another place to get a quote from try Queanbyan Motor Builders, they built my engine and I havent had any issues with there work. Dont bother doing it your self, its not a pulsar or a holden.... you dont want anything else going wrong, if it can it will.