SPV client will consider longest chain valid without verifiying is it valid or not. So an attack factor is that some evil miner with big hashrate could create an invalid chain and beat the number of blocks on valid chain to fool SPV clients.
That is why full nodes exist. SPV clients usually connects to various full nodes to get the network information. Full nodes will be rejecting those with invalid network rules. It is unlikely for anyone to have a big enough hashrate to outpace the current chain and if they have, a 51% attack would've been better.
But if that evil miner has the ability to create longer invalid chain he has the ability to make Selfish Mining attack also. Which will be much more profitable for him with the block rewards.
And the full nodes are not going to accept your coins. You have effectively created another chain that is diverged from the main blockchain.