应该说与主语人称的搭配没什么讲究,倒是在语义上有差别:
would do / have done 仅表示“就会/ （过去）就会.
should do / have done 表示 “应该会/ （过去）应该会.
也就是说,should 暗含按道理或按事情发生的可能性应该怎么样的意思,而would却没有这样的意思.would可能含有乐意的意思.比较：
If I were you,I would do it.如果我是你,我就会做这件事.
If I were you,I should go there.如果我是你,我应该会去那儿.
If he had had the momen,I would have taken it.如果我有钱,我就会买下它了.
If he had started earlier,he should have completed it.如果他开始得早一些,他应该完成了.
由于should 暗含按道理或常理应该怎么样的意思,所以有时用来批评人,如：
You should have handed it in yesterday!你应该昨天就交了它的!(可事实上你没交.这显然是在责怪对方).
希望我已经讲清楚了.